Synthesis of Organic and Bioorganic Nanoparticles: An Overview of

Chapter 2Synthesis of Organic and BioorganicNanoparticles: An Overviewof the Preparation Methods

Joachim Allouche

Abstract Since the emergence of Nanotechnology in the past decades, thedevelopment and design of organic and bioorganic nanomaterials has become animportant field of research. Such materials find many applications in a widerange of domains such as electronic, photonic, or biotechnology, which con-tribute to impact our society and our way of life. The improvement of propertiesand the discovery of new functionalities are key goals that cannot be obtainedwithout a well controlled and a better understanding of the preparation methodswhich constitute the starting point of the design of a specific organic material. Inthis context, this chapter gives a general but non-exhaustive overview of themethods of preparation of organic and bioorganic nanoparticles. Some generaldefinitions about organic nanoparticles and description of organic compounds aregiven before describing the most common methods used divided into twofamilies, the two-step and one-step procedures. The major part of the two-stepprocedures is based on an emulsification step followed by generation of nano-particles through different mechanisms such as precipitation, gelation, or poly-merization. The one-step procedures are founded on generation of nanoparticlesthrough different techniques such as nanoprecipitation, desolvation, or dryingprocesses without preliminary emulsification step. For each method, thedescription is supported by several examples and focused on the explanation ofthe general mechanisms and of the major key parameters involved in the control

J. Allouche (&)IPREM-ECP, Université de Pau et des Pays de l’Adour (UPPA),Technopôle Hélioparc, 2 avenue du Président Angot, 64000 Pau, Francee-mail: [email protected]

R. Brayner et al. (eds.), Nanomaterials: A Danger or a Promise?,DOI: 10.1007/978-1-4471-4213-3_2, � Springer-Verlag London 2013

27

of the nanoparticles formation. In addition, since emergence and improvement ofsyntheses are often associated to development of experimental setups, techno-logical aspects are also mentioned.

2.1 Introduction

Organic nanoparticles can be commonly described as solid particles composed oforganic compounds (mainly lipids or polymeric) ranging in diameter from 10 nmto 1 lm [1, 2]. Over the past decades, this type of nanoparticles has met a greatexpansion and intensive investigations due to their high potentialities in a widespectrum of industrial areas ranging from electronic to photonic, conductingmaterials to sensors, medicine to biotechnology, and so forth [3–13]. Therefore,the choice of the synthetic route is central to optimize the final properties ofnanoparticles designed for a specific application. This choice has to be guided by aseries of factors such as physico-chemical parameters of the organic compound,chemical composition, nanoparticles diameter, structure, morphology, or envi-ronmental considerations which constitute definitely an increasingly incontro-vertible criterion. Consequently, a suitable preparation method cannot bedissociated from a real compromise chosen in function of the different constraintswhich have to be overcome to design well-controlled organic nanomaterials.

This chapter focuses on the description of the most used preparation methodsreported in the literature for the preparation of organic nanoparticles. It starts bygiving some general definitions on the different types of nanoparticles and featuresof organic compounds. The second part is devoted to the description of thepreparation methods highlighting the general principles and mechanisms involvedand the parameters governing the particles formation and their properties.

2.2 Definition and Description of the Different Typesof Particles

2.2.1 Structure and Morphology

Nanoparticles can be divided into main two groups: nanospheres and nanocap-sules (Fig. 2.1). Nanospheres are considered as matrix particles whose entiremass are solid whereas nanocapsules are composed of a liquid or empty coresurrounded by an organic solid shell. Nanospheres and nanocapsules are gen-erally spherical but non-spherical shape can be encountered. The obtaining of thedifferent types of nanoparticles depends evidently on the methods selected forthe preparation.

28 J. Allouche

2.2.2 Organic Materials Composing the Particles

2.2.2.1 Polymeric Nanoparticles

Polymeric nanoparticles constitute by far the most studied organic particles in theliterature [14–18]. Although polymeric nanoparticles can be designed for a widespectrum of applications, two major families can be distinguished. The first one isrelated to nanoparticles elaborated for drug delivery and/or for biomedical pur-poses [19–22]. In this case, the macromolecules require biodegradable orbiocompatible properties. Number of synthetic or natural polymers can be usedand the most widely used are reported in Table 2.1. Despite the great potential ofpolymer chemistry today, one can observe that only a limited number of moleculescan be used as constituents of drug delivery nanocarriers. This is particularly dueto the drastic constraints and requirements which characterized in vivo applica-tions in terms of toxicity and biocompatibility.

The second family of polymeric particles is constituted of conjugated polymericnanoparticles that exhibit electronic or opto-electronic properties [15, 23]. Amongthese conjugated polymers; polyaniline, polypyrrole, polyacetylene, and theirderivatives have been widely studied for their intrinsic conductivity [24–30], whilepolythiophenes, polyfluorenes, poly(p-phenylenevinylene)s, and poly(p-phenyle-neethynylene)s derivatives [31–38] have rather been studied for their electro-optical and photoluminescence behaviors.

2.2.2.2 Solid Lipid Nanoparticles

Solid lipid nanoparticles (SLNs) are composed of lipid matrices derived generallyfrom glycerol esters of fatty acids [39–41]. The lipid compound is characterized by amelting temperature above 37 �C in order to ensure solidification at physiologicaltemperature. Due their high stability (several years), good biocompatibility and lowtoxicity, SLNs are considered as promising drug delivery systems and a goodalternative to polymeric nanoparticles especially for parenteral method. But the limitof this type of particles lies in the fact that the majority of drugs have a poor solubilityin lipids [42]. Ongoing investigations are conducted to increase encapsulations ratesusing nanostructured lipids matrices or lipid-drug conjugates [43, 44].

Fig. 2.1 The different typesof nanoparticles.a Nanospheres,b nanocapsules

2 Synthesis of Organic and Bioorganic Nanoparticles 29

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30 J. Allouche

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32 J. Allouche

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2.3 Methods of Preparation of Nanoparticles

The preparation of organic and bioorganic nanoparticles is divided into two mainmethods [14, 16, 17]. The first approach is based on a two-step procedureinvolving generally the preparation of an emulsification system during the first stepcarried out to generate nanodroplets of definite sizes wherein organic compounds(polymer, monomer, lipid) are previously solubilized. The strategies of emulsifi-cation developed in the literature differ from their high- or low-energy stirringprocedures. The nanoparticles are formed in the second step of the process byvarious mechanisms such as precipitation, gelation, or polymerization.

The second approach consists in conduction of one-step procedures whereemulsification is not required prior to the formation of nanoparticles. The methodsare generally based on the precipitation of organic compounds in solution occuringthrough different routes including nanoprecipitation by solvent displacementor self-assembly mechanisms induced by ionic gelation or by the formationof polyelectrolyte complexes. A few other methods have also been reportedrecently based on strategies involving spray-drying [45, 46], supercritical fluidtechnologies [14, 47, 48], or piezoelectrical ways [49].

2.3.1 Two-Step Procedures Based on Emulsification

2.3.1.1 Emulsions and Methods of Emulsification

The term emulsion is defined basically as a mixing of two or more totally orpartially immiscible liquids obtained in the presence or absence of a surface activeagent. Generally, depending on the type of dispersed phase and of the dispersionmedium, o/w (oil in water) direct emulsion or w/o (water in oil) inverse emulsioncan be formed but more complex systems such as O/O (oil in oil) or multipleemulsions of different kinds (W/O/W, O/W/O, W/O/O) can also be obtained(Fig. 2.2). Depending on the sizes of droplets, the emulsion formed can be clas-sified into three main categories: a microemulsion type which is characterized by athermodynamically stable behavior with droplet diameters ranging from 10 to100 nm and a miniemulsion or a macroemulsion systems that are both thermo-dynamically unstable with drop sizes comprised between 100 nm and 1 lm and upto 1 lm, respectively [50–52].

Over the past decade, methods to prepare suitable emulsions with nanoscaleddroplets to design organic nanoparticles have been considerably evolved due to thetechnological development of emulsification devices and due to the expansion oflow-energy stirring routes in constant progress, thanks to environmentalconstraints. Indeed, low- and high-energy emulsification techniques constitute twostrategies to obtain nanodroplets and consequently nanoparticles.

34 J. Allouche

Low-energy Emulsification Methods

Nanoemulsions can be generated by low-energy emulsification techniques clas-sified into two groups in the literature. The first one is the so-called spontaneousemulsification [50, 51, 53–55] obtained by the rapid diffusion of a water-solublesolvent, solubilized first in the oily phase, moving toward the aqueous one whenthe two phases are mixed. This phenomenon, presented as a good alternative ofhigh-energy methods, has been described in several works as a solvent displace-ment method [56–61] (also called the ‘‘Ouzo effect’’) where nanoemulsion isobtained by a rapid diffusion of an organic solvent generally acetone or ethanolfrom the oily phase to the aqueous phase. Direct O/W emulsion as well as inverseW/O emulsion can be produced by this way. Spontaneous emulsificationmechanism originates from interfacial turbulence related to surface tension gra-dient produced by the diffusion of solutes between two phases [54]. It is assumedthat drops are created by interfacial corrugations caused by a Marangoni effectcausing severe interfacial fluctuations. In the case of the presence of surfactants,fluctuations of the interfacial amphiphile concentration create local supersaturationof the surfactant at interface resulting in the nucleation and growth of drops [62–64]. The study of the basic mechanism involved can be illustrated by a simpleternary water/alcohol/oil ternary system through the determination of a phasediagram which is essential to describe the diffusion path and to target the spon-taneous emulsification domain [54]. In such diagram, as illustrated in Fig. 2.3, atwo-phase equilibrium region occurs corresponding to the spontaneous emulsifi-cation (SE) domain. Upon dilution, the diffusion path of the water phase crossesthe SE region inducing spontaneous emulsification and the formation ofnanoemulsion.

In the field of nanoparticles synthesis, more complex systems are involved andthe ternary diagram has to be adjusted to take into account the potential influencesof additional components such as monomers, polymers, or surface active agents onthe modification of the diffusion pathway. Among all key parameters modifyingthe droplet sizes and stability of nanoemulsions (pH, water and oil proportions,solvent type and content, etc.), temperature strongly affects the solubility of theorganic solvent in the water and the oil phase and modifies consequently thediffusion process.

Another route to produce spontaneous emulsification is the so-called emulsioninversion point method (EIP) carried out at constant temperature. The method is

Microemulsions10-100 nm

Miniemulsions100-1000 nm

Macroemulsions> 1 µm

(a) (b) (c) (d)Fig. 2.2 Different types ofemulsions. a Microemulsion,b nanoemulsion, c simplemacroemulsion, d multipleemulsion


based on a progressive dilution with water or oil of a microemulsion or liquidcrystals leading kinetically stable nanoemulsions [65–73]. Indeed, by changing thewater and oil proportion in microemulsion network, interfacial instabilities areoccurring resulting in the destabilization of the thermodynamically stable micro-emulsion structure into nanoemulsions. Keeping in mind that the best conditionshave to be found to obtain the smallest drop sizes, determination of phase diagramsis also required in this case and have to be adjusted carefully in function of theformulation used for the design of nanoparticles (type of monomers, polymers,initiators, drug encapsulated, etc.).

The third group of low-energy emulsification methods is the so-called phaseinversion temperature (PIT) method [74, 75] offering the main advantages toobtain nanoemulsions with a potentially low amount of surfactant (typically lessthan 5 wt %), a reduced toxicity since no organic solvent is needed, and a rela-tively easy handling. It makes the method suitable for biotechnology applications(nanomedecine, pharmaceutical science or cosmetics) since degradation of drug tobe encapsulated is avoided. This versatile way uses the ability of polyethyleneoxide (PEO)-based surfactants to change their affinity for water and oil in functionof temperature leading to a so-called ‘‘transitional phase inversion’’ of emulsions.Typically, when temperature increases, the PEO blocks undergo dehydrationwhich modify the amphiphilic character of surfactants toward higher lipophilicbehavior. Consequently, an O/W emulsion produced at low temperature invertsinto a W/O one upon a temperature rising. Likewise, in the transitional region attemperatures for which the surfactant exhibits similar affinity for the two immis-cible phases, ultralow interfacial tension and low curvature create bicontinuousmicroemulsion nanostructures. Therefore, the principle of the PIT method is tosuddenly breakup such structures maintained at the PIT temperature by rapidcooling or dilution generating immediately kinetically stable nanoemulsions[76–81]. Once again, phase diagram has to be established to determine the tran-sitional inversion region in function of the formulation parameters (temperature,

Water Oil

Alcohol

Spontaneous emulsification(two-phase equilibrium region)1

1’

2

3

4

Fig. 2.3 Diffusion path in awater/alcohol/oil system.Segment (1–2): diffusion pathof the aqueous phase.Segment (2–3): interfacialequilibrium. Segment (3-4):diffusion path of the oilyphase. Segment (10-2):crossing of the two-phaseequilibrium region inducesspontaneous emulsification

36 J. Allouche

oil type, salinity, etc.) and of the water to oil ratio (WOR). This is suitable to targetthe inversion path which has to be followed to produce nanoemulsions. The groupof Salager et al. has developed an empirical ‘‘Hydrophilic Lipophilic Deviation’’(HLD) expression (Eq. 2.1) based on the difference of the chemical potential ofsurfactants in the two phases [82–86].

HLD ¼ a� EON þ bS � kACN þ tDT þ aA ð2:1Þ

where EON is the number of ethylene oxide groups for surfactants, S is the weightpercentage of electrolytes in the aqueous phase, ACN the amount of carbonnumbers of the n-alcane composing the oily phase, DT the temperature differencefrom the reference temperature (25 �C), A the weight percentage of alcoholpotentially added, a, k, t the parameters in function of the used surfactant, a, aconstant function of the types of alcohol and surfactants, and finally b a constantfunction of the nature of the added electrolytes. It comes that HLD can be cal-culated and its value depends on the different formulation parameters of the systemrepresenting by the terms of the equation. HLD = 0 corresponds to the optimumformulation where the surfactant has equal affinity to water and oil whereas HLD[ 0 and HLD \ 0 represent higher lipophilic or hydrophilic behaviors, respec-tively. Moreover, formulation-composition maps can be constructed as illustratedin Fig. 2.4 [83, 87–91]. For a given system at constant stirring conditions and for afixed surfactant concentration, zones of macroemulsion, multiple emulsions, andtransitional region appear. It allows the identification of the best path conditions(especially the temperature range) to produce transitional inversion of emulsion[91–96]. Although transitional inversion presents many advantages for the prep-aration of nanoparticles, this method is still anecdotal and very recently developedin the literature for the production of lipid nanocarriers and nanocapsules orpolymer nanoparticles compared to high-energy emulsification techniques.

W/O> 0 2

o/W/O

w/O/W

O/W

HLD 0

< 01

Fig. 2.4 Typical ‘formulation-composition’ map for a given water/surfactant/oil system showingthe emulsion inversion zones and the different types of emulsions. Path (1–2) illustrates a possibletransitional inversion from O/W emulsion to nano-W/O emulsion inducing by the crossing of theultra-low interfacial tension region HLD = 0


High-Energy Emulsification Methods

Most of methods of preparation of nanoemulsions are based on mechanical pro-cesses related to high-energy stirring techniques. In this field, the most commondevice consists in a rotor–stator apparatus in which a shear stress is applied toinduce deformation of pre-emulsion droplets leading to their breaking into smallerones of uniform size (Fig. 2.5). The final diameter of the daughter droplets ismainly determined by the applied stress and only weakly depends on the viscosityratio between the dispersed and the continuous phase [97–102].

Sonication is also a process widely used in the literature for nanoemulsification[50, 103–114] and for the generation of polymer or lipid nanoparticles [115–127].This process of ultrasound emulsification is performed under high frequency wherelarge drops are generated by the instability of interfacial waves [104, 105]. Thedrops are subsequently broken into smaller ones through a cavitation mechanism.Some authors have shown that optimal conditions for sizes reduction and betternanoemulsion stability are obtained using high-power setting for short exposuretimes [103]. Indeed, longer exposure times produce degradation of surfactant byradicals which form during the thermal decomposition of water [128, 129].

In the past few years, others machines have been designed to obtain dropletswith more reproducible calibrated sizes and well-defined characteristics in theview of large-scale production. These machines have been related to microfluidictechniques that constitute at the moment an intense research area in progress[130–137]. The principle is based on an extrusion mechanism where the dispersedphase is forced to permeate through a microfiltration device to calibrate droplets inthe continuous phase (Fig. 2.6). The microfiltration units differ from their tech-nological design and can be engineered as porous membranes, flow-focusing,Y-shaped or T-type microchannels [138]. Polymeric particles of PLGA–PEG[139], PCL [140], or alginate [141] have for example already been produced bythis technique.

Fig. 2.5 Scheme of theprinciple of emulsificationwith a rotor–stator device

38 J. Allouche

2.3.1.2 Generation of Nanoparticles from Emulsion

Precipitation Induced by Solvent Removal

Macromolecules dissolved in the dispersed phase (mainly the oily one) of theemulsion can undergo precipitation upon removal of the organic, often volatilesolvent. To perform this solvent extraction, several methods such as solventevaporation, solvent diffusion, or salting-out procedures have been developed andconstitute by far the most famous routes carried out in the field of organicnanoparticles formation from emulsified systems. It comes from the versatilitycharacter of this way that can be applied to a wide range of organic compoundsincluding synthetic polymers and natural bioorganic macromolecules such aschitosan, polysaccharides, alginate, or gelatin.

Solvent Evaporation

The method consists in the preparation of nanoemulsion formulated with a poly-mer dissolved in a volatile solvent solution [142]. Dichloromethane and chloro-form are the most widely used solvents but are often replaced by ethyl acetate, lesstoxic and hence much more adapted to the synthesis of controlled release systemswhere drug encapsulation is generally involved. In this method performed undervacuum, suspension is produced by evaporation of the polymer solvent fromemulsion droplets which is allowed to diffuse through the continuous phase [19].This slow procedure involves first a fast evaporation period during which at least90 % of the polymer solvent is evacuated followed by a slow evaporation periodwhere the few percent of the remaining solvent is extracted. During the first step,droplets sizes dramatically decrease to reach a minimum value due to the highsolvent lost. In contrary, the second step is characterized by a significant increaseof the droplet diameters in reason to coalescence. This coalescence process can beaccentuated in the case of a polymer having interfacial adsorption propertieswhereas for polymers characterized by poor surface active properties, the coa-lescence is reduced. In addition, partially miscible solvents in the preparation ofemulsion can be used and change the conditions of evaporation. The volatilesolvent removal can be in this case realized by distillation [143].

Numerous examples of nanoparticles preparations by solvent evaporation canbe found in the literature with various polymers such as PLGA [144–147], PLA[148, 149], or PCL [150] (Fig. 2.7). Also, amphiphilic copolymers (PEG-PLA

Membrane

Oily phase

Aqueous phase

Fig. 2.6 Scheme of theprinciple of emulsificationusing a microfiltration devicebased on a porous membrane


[151, 152], PEG–PLGA [153], polysaccharides-PCL [154, 155]) nanospheres canbe produced by this method with no need of surfactant to ensure the emulsionformation and the stability of the final nanoparticles suspension.

Solvent Diffusion

The solvent diffusion method also called solvent displacement method (Fig. 2.8)requires a polymer solvent partially soluble in water [156–158]. The preparation ofemulsion involves two immiscible phases, but where the oil dispersed one is com-posed of water saturated with the polymer solvent and where the continuous one iscomposed of oil saturated with water. This can be obtained by mixing the polymersolvent and water and waiting the decantation to get a two-phase system. At thebottom and at the top of the resulting system, the solvent saturated water and the

Fig. 2.7 Examples of nanoparticles produced by the emulsion–solvent evaporation method.a PLGA nanoparticles (adapted with permission from [145]). b PCL nanoparticles (adapted withpermission from [150])

Fig. 2.8 Scheme of preparation of nanoparticles by the emulsion–diffusion procedure. (1)Partially water miscible solvent saturated with water. (2) Water saturated with solvent. (3)Solvent saturated with water ? dissolved polymer. (4) Water saturated with solvent ? surfac-tant. (5) Emulsification. (6) Dilution with water and formation of polymeric nanoparticles fromemulsion

40 J. Allouche

water saturated solvent can be collected, respectively. Oil-in-water emulsion isprepared with the previous two immiscible phases and subsequently diluted with ahigh quantity of water. This leads to the precipitation of the polymer induced by arapid diffusion of the organic solvent from the oil droplets to the continuous phase.Several polymer solvents can be used such as ethyl acetate [143], isopropyl acetate[159], benzyl alcohol, propylene carbonate [160], and surfactants such as pluronicF68� or Polyvinyl alcohol (PVA) is often employed to play a role in the stabilizationand sizes of the emulsion droplets. PLA [161] (Fig. 2.9), PLGA [162–164], and PCL[157] are the most common and suitable polymers used but gelatin or chitosannanoparticles [165–167] have also been synthesized by this method.

In addition, this method involves a pure diffusion mechanism where the dropletsizes drop suddenly in a millisecond time scale during solvent extraction andpolymeric nanoparticles formation. Among all factors impacting the reduction ofthe particle diameters, one can cite the increase of the miscibility of water with theorganic solvent or of the stirring rate and the use and concentration of stabilizingagents added in the emulsion. On the contrary, the rise of the polymer concen-tration leads to significant increase of the particle sizes and polydispersity.Generally, nanospheres are produced by this technique but adding a small amountof oil in the organic phase results in the generation of nanocapsules.

Salting-Out

Very close to the solvent-diffusion method, this process involves emulsificationwith a polymer solvent generally acetone that is normally totally miscible withwater. Actually, the artifice used to emulsify water and acetone is to dissolve highcontents of salt or sucrose in the aqueous phase to provoke a strong salting-outeffect modifying the solubility of water with the solvent [168]. The emulsion canhence be formed with a polymer dissolved in the solvent droplets. Particles pre-cipitation is induced, as in the solvent-diffusion process, by diluting the emulsionand adding a large amount of water in the continuous phase to drop the saltconcentration and to cause extraction of the solvent out of the droplets.

The suitable electrolytes for this process are generally magnesium chloride[169–171] or calcium chloride [172] but salting-out can also be produced bysaturation of the aqueous phase by PVA [173] which acts in addition as a

Fig. 2.9 Scanning ElectronMicroscopy images of PLAnanoparticles obtained withthe solvent diffusion method(adapted with permissionfrom [161])


viscosity-increasing agent and emulsion stabilizer. Poly(ethylene oxide) [169],PLGA [172, 174], or poly(trimethylene carbonate) [175] particles, for instance,have been synthesized by this method with diameters in a 100-500 nm range. Thestirring energy required for this method is also reduced which provides lowerparticle diameter and less pronounced influence of the polymer concentration andof the stirring speed on the emulsion droplets in comparison to more conventionalemulsification routes.

Gelation of the Emulsion Droplets

Another method to obtain nanoparticles after nanoemulsification is to gelifypolymer or crystalize lipid dissolved in the droplets [39, 176]. For instance, in thecase of agarose [177] or gelatin [127], the preparation of the nanoemulsion can beperformed at moderate high temperature above the melting point and subsequentcooling down induces gelation of the emulsion droplets and their conversion intonanoparticles. The same procedure can be applied for the production of solid lipidnanoparticles by crystallization of the lipid under the melting temperature [39].Gelation can be produced by other physicochemical factors such as pH or byadding components like divalent cation (generally calcium) to induce ionic gela-tion [178]. Polysaccharides biopolymers such as alginate or pectin are particularlyadapted since their chemical compositions based on uronic acids functions areresponsive to pH or to complexation with cations. In this kind of gelation, twoemulsions are generally prepared, the first one containing the dissolved biopolymerand the second one containing the pH controlling agent or the cation. The twoemulsions are mixed under strong agitation to provoke droplets collision which isessential to induce gelation and hence formation of nanoparticles.

Polymerization in Emulsion

Among all techniques used for the generation of nanoparticles from emulsions,polymerization is the subject of the abundant literature since well-defined anddesired nanoparticles properties for a particular application can be attained throughthis process [179–184]. In this case, instead of the previously described techniquesfor which a solution of a preformed polymer is prepared, macromolecules formthrough polymerization of monomers. The major emulsion polymerization tech-niques can be classified into different methods such as conventional emulsionpolymerization, surfactant-free emulsion polymerization, as well as mini- (ornanoemulsions) and microemulsions polymerizations which differ from thekinetically and thermodynamically different emulsion behaviors. In addition, wecan cite interfacial polymerization, a very useful method for the preparation ofnanocapsules and living/controlled radical polymerization process that offers atthis moment a much better control of the polymer characteristics in comparison toolder conventional polymerization techniques.

42 J. Allouche

Conventional Emulsion Polymerization

This method can be considered as the traditional way to generate nanospheres fromemulsion polymerization and is still widely used nowadays. Generally, the com-ponents are water, a monomer of low water solubility, a water-soluble initiatorwhich may be an ion or a free-radical and a surfactant. Polymerization starts in thiscase when a monomer molecule collides with an initiator molecule. Another wayconsist in initiating radical from the monomer itself using UV irradiation, ultra-sonication, or c-radiation. Before or after the termination of the polymerization,the solid particles can be formed. Various types of polymeric nanoparticles couldbe produced by this technique such as poly(vinylcarbazole) [185], poly(methyl-methacrylate) [186, 187], polystyrene [188–195], or poly(alkylcyanoacrylate)[196–201] nanoparticles. In the latter case, anionic polymerization for whichinitiation occurs by any nucleophilic groups like hydroxyl groups of water is themost common way. In addition, performing anionic polymerization in acidicconditions slows down the rate of reaction and hence favors the formation ofnanospheres instead of polymer aggregates. The particles sizes depend on thesurfactant used and can be obtained generally in a 50–300 nm range.

Surfactant-Free Emulsion Polymerization

In contrary to conventional emulsion polymerization, surfactant-free emulsionpolymerization is performed without emulsifier offering the major advantage to obtainnanoparticles without any step of surfactant removal [202–208]. This could beenvironmentally, energetically, and time-consuming advantageous especially forhigh-scale productions of nanoparticles. The ingredients in such emulsifier-free systemare water, a water-soluble initiatior (like potassium persulfate), and monomers whichare generally vinyl or acrylic. The stabilization of nanoparticles in formation is ensuredin this case by the use of ionizable initiators or ionic co-monomers. Two mechanisms ofpolymerization are involved, micellar-like nucleation [209, 210] and homogeneousnucleation [211–216] that differs from the aqueous solubility of the monomer. PMMAnanoparticles have been obtained by this technique using microwave irradiation[217, 218], redox initiation [219], or laponite clays as stabilizing agent for the emulsion[220]. The general trend is that monomer concentration is a key parameter influencingthe particle sizes as illustrated in Fig. 2.10 where the increase of the monomerconcentration increases the particle size.

Polyacrylate nanospheres were also obtained and some authors have shown thatultrasonic irradiation or the concentration of a stabilizing agent (4-styrene sulfonicacid) altered the particle sizes and distribution [221]. Polythiophene nanoparticleshave been equally successfully prepared by Fe3+ oxidative polymerization [222]where the difference in the polymerization rates of monomers and the electrostaticattraction between sulfonate and Fe3+ ions results in the production of core–shellmorphology with a size distribution ranging from 300 to 800 nm.

Although surfactant-free emulsion polymerization is considered as a simple and‘‘green’’ way for polymeric nanoparticles preparation, improvements have to be


conducted in the future to obtain monodisperse and more precisely controlledparticle sizes.

Miniemulsion Polymerization

This method can be distinguished from conventional and surfactant-free emulsionpolymerization by the generation of nanoemulsions using high-energy methods(Fig. 2.11) and generally a low molecular mass compound as co-stabilizer priorinitiating polymerization [223–231]. The typical formulation consists in water,monomer mixture, co-stabilizer, surfactant, and initiator. The droplets of thenanoemulsion are generally composed of a pure monomer phase stabilized by asuitable adsorbed surfactant. The polymerization mechanism widely employed isradical polymerization which is initiated in the emulsions droplets via the incor-poration, in most cases, of the initiator in the continuous phase. The generalmechanism assumed in the literature is the droplet nucleation mechanism sug-gesting that radicals are generating in each monomer droplet taken as individualreaction site [180, 232]. The number and size of particles do not consequently varyduring the polymerization process. The choice of the initiator and its solubility hasevidently a great influence on the final particles properties especially the particlesize. Even if inverse nanoemulsion polymerization is possible using hydrophilicingredients [233–235], in most cases, the hydrophobic character of the dispersedmonomer phase requires an oil-soluble initiator which is more suitable to obtainwell-defined nanoparticles.

Although radical polymerization is often selected for the generation of nano-particles in miniemulsion polymerization, non-radical polymerization methodssuch as polyaddition [236, 237], anionic polymerization [238], or metal-catalyzedreactions [239] are less aggressive for drug encapsulation applications and can alsobe used. Some authors [236, 237] have demonstrated for instance the preparation

Fig. 2.10 Influence ofmonomer concentration ondispersity and averageparticle size of PMMAnanoparticles obtainedthrough surfactant-freeemulsion polymerization(reprinted with permissionfrom [217])

44 J. Allouche

of polyurethane latex nanospheres using reaction between diisocyanate and acti-vated diol in nanoemulsion droplets. The low water solubility of reactants and theslower polymerization kinetics than emulsification are the main key factorsinducing the successful synthesis.

Microemulsion Polymerization

The main difference between microemulsion and miniemulsion polymerizationmethods relies on the kinetic character of the dispersed phase produced in theemulsified system. Indeed, in contrary to miniemulsion, microemulsion is a ther-modynamically and spontaneous stable system prepared with a high quantity ofsurfactant and characterized by an interfacial tension at the oil/water interfaceclose to zero [52, 64]. The generation of nanoparticles through microemulsionpolymerization generally results in smaller particle size (typically less than 80 nm)than in miniemulsion polymerization processes. A water-soluble initiator isintroduced in the aqueous phase initiating the polymerization in only some swollenmicelles of the microemulsion containing the monomer. As time elapses, theosmotic and elastic influence of the polymeric chains in formation destabilizes themicroemulsions leading to an increase in the particle size, to the formation ofempty micelles, and to a secondary nucleation [232, 240].

In the literature, various formulations have been investigated to prepare forinstance nanoparticles of polyvinyl acetate [241, 242], polyaniline [243–246],polyacrylamide, or polypyrrole [247]. The studies highlighted the critical factorsthat influence the final particle properties as the type of initiator and concentration,the surfactant, the concentration of monomer, and the reaction temperature.

Microemulsion polymerization has a great potential in many applications butretains important drawbacks relating to its high dilute formulation and its highamount of surfactant which limit in a large extent the commercial use of thistechnique.

Fig. 2.11 Scheme of nanoparticles preparation from a typical miniemulsion polymerizationmethod. a Pre-emulsification b nanoemulsification using a high shear device c formation ofpolymeric nanoparticles upon addition of initiator


Interfacial Polymerization

Interfacial polymerization is characterized by the polycondensation of monomersat the droplet interface leading to the generation of mainly nanocapsules instead ofnanospheres. Different strategies have been developed (Fig. 2.12) which dependon the formulation selected and the choice of monomers introduced either in thecontinuous and/or in the dispersed phase.

The first way consists in introducing the monomer in the continuous phase ofthe emulsified system. The monomer can subsequently react with the emulsiondroplets to form nanocapsules. Due to the hydrophobic character of the majority ofmonomers used, the emulsions prepared in this case are generally of the W/O type.Thus, a good solubility of the monomer for the external phase and its sufficient

Fig. 2.12 Scheme of the different strategies of interfacial polymerization. (1) Introduction of themonomer in the oily phase. (2) Introduction of monomer in the aqueous phase. (3) Introduction ofmonomers in the oily and aqueous phase. (4) Polymerization using a membrane reactor device

46 J. Allouche

reactivity toward the aqueous phase are critical factors that influence the success ofthe procedure. For instance, in the case of the polymerization of alkylcyanoac-rylate such as isobutyl-cyanoacrylate, hydroxyl ions catalyze the reaction and w/onanocapsules can be generated [248–255]. Lipophilic diisocyanate can also beused due to its high hydrolyzable properties which induce conversion of the iso-cyanate functions into amine [256]. The amine function can react subsequentlywith another monomer molecule leading to polymerization at droplet interface.Another interesting work showed by Jang et al. [257] is the possibility to obtainfrom this first strategy different architectures of poly(3,4-ethylenedioxythiophene)(PEDOT) nanomaterials. The method is based on a so-called ‘‘Surfactant Medi-ating Interfacial Polymerization (SMIP)’’ method allowing selective synthesis ofeither nanocapsules or mesocellular foams in function of the concentration ofquaternary ammonium-based surfactants (Fig. 2.13).

In the second strategy, the monomer is introduced in the droplet phase andpolymerization occurs by reaction with the continuous phase or by adding initiatorin the external phase [258, 259]. Initiator can also be added in the dispersed phase

Fig. 2.13 TEM images of PEDOT nanocapsules and mesocellular foams. a Nanocapsulesprepared using 0.15 M of DeTAB. b Mixture of nanocapsules and mesocellular foams obtainedusing 0.20 M of DeTab. c Mesocellular foams prepared using 0.30 M of DeTab. d Theconcentration ranges for formation of PEDOT nanomaterials as a function of the surfactanthydrocarbon length and polymerization temperature. DeTab Decyltrimethylammonium bromide,OTAB Octadecytrimethylammonium bromide, DoTAB Dodecyltrimethylammonium bromide.(adapted with permission from [257])


and polymerization is initiated by temperature. In this case, as polymerizationproceeds; gradual segregation of the polymer in formation toward the water/oilinterface creates nanocapsules. Another interesting procedure that could be pos-sible is the simultaneous generation of interfacial polymerization and nanoemul-sion using solvent diffusion. For instance, alkyl cyanoacrylate monomers can beintroduced in the oil dispersed phase containing a water miscible organic solvent[62, 260–263]. Polymerization can thus be initiated along with the rapid solventdiffusion to the aqueous continuous phase. Nanocapsules are hence formed at thesame time than the nanoemulsion.

Finally, the third route involves two reactive species of different solubilitiesintroduced, respectively, in the continuous and dispersed phases. The reactiontakes place at the interface of the two liquids. This method is the most commonlyused for the generation of nanocapsules. Evidently, the type of monomers addeddefines the nature of the final polymer shell. For instance, polyamides [264],polyurea [265], polyurethanes [57] nanocapsules can be produced by this tech-nique using generally the reaction of isocyanate functions with activated diol.Some authors have shown that the thickness of the polymer wall is independent ofthe concentration of the lipophilic monomer but varies with the amount of thehydrophilic monomer added [264].

From the strategies described above, different methods have been developed todesign nanoparticles by interfacial polymerization but a main problem inherent tothe well control of the particle size remains. In the recent past years, the use ofmembrane reactors has been developed to overcome this problem since a bettercontrolled addition of one reactant to another reactant can be achieved [266, 267].Indeed, this versatile technique allows the preparation of either nanospheres ornanocapsules and offers the possibility to target the nanoparticle size by a suitablechoice of the membrane parameters (membrane pore radius, cross-flow velocity,shape of the pore opening, transmembrane pressure, etc.) and the formulationfactors (viscosity of the dispersed and continuous phase, type of surfactant, etc.)[268, 269]. However, nanoparticles preparation by membrane reactors is oftenconsidered as an expensive process due to a complicated technological develop-ment which constitutes a major drawback to its widespread utilization.

Controlled/Living Radical Polymerization

Main limitations caused by fast radical–radical terminations are inherent to radicalpolymerization including the control of the molar mass and mass distribution, theend-functionalities and the macromolecular architecture. To obtain a better controlof such parameters, the controlled/living radical polymerization [270–272] hasemerged as a new field in the recent past years helped by the industrial production ofhydrophilic polymeric nanoparticles designed specifically for biomedical applica-tions and by environmental concern with the development of the so-called ‘‘greenchemistry’’. The principal methods of controlled/living radical polymerization arenitroxide-mediated polymerization (NMP) [273–277], atom transfer radical poly-merization (ATRP) [278–284], and reversible addition and fragmentation transfer

48 J. Allouche

chain polymerization (RAFT) [285–287]. Suitable properties of nanoparticles can beobtained by optimizing different parameters such as the nature and concentration ofthe monomer, surfactant, initiator, and the type of emulsion but above all the type andconcentration of the mediating (control) agent. Several kinds of polymeric nano-particles have been synthesized by this technique such as for instance poly(butylacrylate) [275, 276, 288], poly(styrene) [277, 286], or poly(methyl methacrylate)[282, 284] nanoparticles with typical particle size in a 30–400 nm range, using eitherNMP, ATRP, or RAFT approaches and different formulations. The presence ofresidual control agent is at this moment the major problem of controlled/livingradical polymerization. For environmental purpose, the removal of control agentneeds to be performed which caused additional difficulties and cost for this process.

2.3.2 One-Step Procedures

2.3.2.1 Nanoprecipitation

Nanoprecipitation method also called solvent displacement method was developedby Fessi et al. [63] in the end of 1980s. It is one of the easiest, most economic, andreproducible routes to produce nanospheres using preformed polymers instead ofmonomers. This method, very close to the previous described spontaneousemulsification technique, is based on the interfacial deposition of a polymer afterdisplacement of a semipolar solvent, miscible with water, from a lipophilicsolution. Three ingredients are required to achieve the process: the polymer, thepolymer solvent, and the non-solvent of the polymer. The polymer can be syn-thetic, semisynthetic, or natural and the most frequently used polymer solvents areethanol, acetone, hexane, methylene chloride, or dioxane. The choice of thepolymer solvent is guided by two factors: a high solubility in water and an easyremoval by evaporation. To satisfy these conditions, acetone is often selected[63, 289, 290] but a binary blend of solvent like acetone with a small amount ofwater or blends of acetone and ethanol [291–293] or methanol [294] can be used.The non-solvent phase is composed of one or a mixture of nonsolvent of thepolymer with eventually the addition of surfactants. The nanoparticles are gen-erated by a rapid diffusion of the polymer solvent in the non-solvent phase bymixing the polymer solution with the latter one. This results in a drop of theinterfacial tension between the two phases causing an increase of the surface areaand the instantaneous precipitation of polymeric nanoparticles. The lipophilicpolymer solution is generally added slowly to the non-polymer solvent but thereverse order also produces nanoparticles. Smaller, more well-defined and nar-rower distribution of the nanoparticle sizes, typically in a 75–900 nm range, can beobtained than those obtained by emulsification solvent evaporation technique.Many parameters are conditioning the final nanoparticle properties such as theorganic phase injection rate, the agitation during addition of the polymer solution,the miscibility of the organic solvent with the non-solvent phase, or the nature of


the polymer/solvent interactions. The type and concentration of added surfaceactive agents also influence the nanoprecipitation process [157, 295] since sur-factants help in the stabilization of the nanoparticles prevented from aggregationwhich is especially useful for long storage periods of suspensions.

The method of nanoprecipitation can be performed with various formulationincluding a wide range of polymers such as poly(e-caprolactone) [295–299],polylactide [300, 301], poly(lactide-co-glycolide) [302, 303], poly(hydroxylbutyrate) [304], or even peptides [305]. Moreover, the process can be applied tonon-polymeric compounds such as cyclodextrin [306] and drug [307].

Finally, nanoprecipitation is a method widely used for the preparation ofpolymeric or non-polymeric nanospheres due its simplicity, rapidity, and repro-ducibility even though the low polymer concentration required limits the recov-ering yield of nanoparticles.

2.3.2.2 Dialysis

Very close to the above described method, dialysis is based on a solvent dis-placement mechanism but includes, in contrary to the conventional nanoprecipi-tation technique, additional tools such as dialysis tubes or semi-permeablemembranes with suitable molecular weight cutoff which serve as a physical barrierfor the polymer [308–310]. Thus, dialysis is performed against a nonsolvent of thepolymer miscible with the polymer solvent. The displacement of the polymersolvent through the membrane induces a progressive loss of solubility of thepolymer leading to the formation of homogeneous suspensions of nanoparticles.According to the solvents used, the morphology and size of the particles can beaffected [311]. Various formulations have been investigated and nanoparticles ofdifferent types of polymers such as poly(lactide)-b-poly(ethylene oxide) [312],polystyrene [313], poly(L-lactic acid)-b-poly(ethylene glycol) [314], poly(c-glu-tamic acid) [311], or cellulose-derived polymers [315] can be obtained by dialysis.

2.3.2.3 Desolvation

The desolvation method is based on a slow addition of a desolvation factor such assalts, alcohols, or solvents in a solution of macromolecules to provoke the pre-cipitation of the polymer [316, 317]. This method, rather similar than othernanoprecipitation methods based on a loss of solubilization of the polymer, ishowever often associated to the generation of biopolymeric nanoparticles. Indeed,desolvation process is generally employed for the production of nanoparticles ofdifferent types of proteins (Fig. 2.14) such as human serum albumin [318–323],bovine serum albumin [324, 325], gliadin [326–328], or gelatin [318, 329–335].The desolvation is often followed by a cross-linking step performed with theaddition of a certain amount of aldehyde (typically glutaraldehyde) to stabilize theformed nanoparticles. In the case of gelatin (type A), a two-step desolvation route

50 J. Allouche

has been developed by Coester et al. [329, 330, 336]. In the first step, the lowmolecular gelatin fractions present in the supernatant is removed by decanting.The sediment is then redissolved and desolvated in a second step at pH 2.5. Thistwo-step process can also be applied to type B gelatin but the pH is adjusted at 12.Polysaccharide particles of chitosan [337] or hyaluronic acid [338] can also beobtained by desolvation but using sodium sulfate as desolvating agent in thesecases.

2.3.2.4 Self-Assembly and Gelation

Polyelectrolytes Complexation

In this case, the organic nanoparticles are obtained based on the association ofoppositely charged macromolecules forming, when mixed in specific conditions,polyelectrolyte complexes. Such particles are widely used and developed as invivo drug delivery carrier of nucleic acids [339, 340]. In this case, nucleic acidsplay the role of drug as well as a component of the drug delivery system. Thepolycations, typically poly(ethylenimine), poly(lysine) or chitosan, are generallyemployed as the opposite (positive) charged compound able to interact with thenegative charges of the nucleic acid phosphate groups [340]. One of the keyparameters to optimize the nanoparticles formation is the ratio N/P of the positiveamine groups noted ‘‘N’’ (as nitrogen) to the nucleic acid negative phosphategroups noted ‘‘P’’. Thus, a value of N/P above one means a polyelectrolytecomplex positively charged where the internal polyelectrolyte chains of the systemare able to be swollen by water.

Fig. 2.14 TEM images ofGelatin (a), Human serumalbumin (b), and Bovineserum albumin (c, d; high andlow magnification,respectively) nanoparticlesprepared by the desolvationmethod (reprinted withpermission from [323, 324,334] respectively)


Other types of complexes can be form based on the association of alginate, anegatively charged polysaccharide, and poly(lysine), a positively charged peptide[341]. Dextran sulfate and chitosan can also interact to form complexes [342–344].

An interesting feature of polyelectrolyte complexes is the possibility to addone polyelectrolyte in excess compared to the other in order to modulate the netcharge of the nanoparticles and to induce colloidal stabilization. Indeed, theexcess of component is segregated at the outer shell of the complex whichproduces a core–shell structure where the surface charge of the nanosphere isconferred by the polyelectrolyte in excess. In addition, the nanoparticle size isinfluenced by the chain length ratio of the macromolecules which conditions themutual role of each electrolyte in the complex. Indeed, the highest molecularweighted compound serves as host for the lowest weighted one which is definedas the guest [342].

‘‘Lock and Key’’ Nanogels

Supramolecular nanoassemblies based on a ‘‘lock and key’’ concept lead nano-spheres formed by neutral association of a certain type of macromolecules thathave been developed recently [345, 346]. These polymers are composed of dextranmodified by the grafting of alkyl chains and a poly(beta-cyclodextrin). Theassembly occurs spontaneously in aqueous medium forming a hydrogel since thealkyl chains of the modified dextran are incorporated as a guest in the hydrophobiccavities of the host poly(beta-cyclodextrin). One of the main advantages of thissystem is the efficiency of the association phenomena which can lead 95 % ofincorporation of the guest in the nanogel as well as a nondependence of theprotocol followed (order of introduction of the polymer solutions, method ofmixing, temperature, etc.). However, the final properties of nanogels depend onvarious factors such as the polymer concentrations, the weight ratio between thehost and the guest, the number of carbons in the alkyl chains, or the percentage ofsubstitution of the glucose units of dextran by the alkyl chains. Finally, thesenanogels used as drug delivery devices of hydrophobic drugs such as benzophe-none and tamoxifen exhibit excellent loading efficiencies (at least 90 %) and awell- controlled release of the drugs over a period of 16 days.

Ionic Gelation

Synthesis of nanoparticles by ionic gelation is commonly performed with bio-polymers especially charged polysaccharides in aqueous medium in very dilutesolution (Fig. 2.15). Indeed, the polymer is dissolved in water with a concentrationbelow the gel point and can react with small ions of the opposite charges to formclusters. These clusters can be stabilized subsequently using oppositely chargedpolyelectrolytes. For instance, using alginate, gelation is typically carried out inthe presence of calcium ions leading to a pre-gel phase which is then stabilized

52 J. Allouche

with polycations such as polylysine [341, 347–350] or chitosan [348, 351–357]. Itis noted that alginate can react with polylysine without addition of cations to forma simple polyelectrolyte complex but a pre-gel phase ensures a more compactstructure of the nanogel. Furthermore, the size of the nanoparticles obtainedgreatly depends on the concentration of the biopolymers and is also influenced bythe molecular weight of the opposite charged macromolecule.

Chitosan nanoparticles can also be produced via ionic gelation. In contrary toalginate, chitosan is positively charged at neutral pH and in consequence, can formnanogels with anionic ions like tri-polyphosphates (TPP). Thus, the pre-gel phaseis induced, as for alginate, in diluted solution with the addition of a small amountof TPP. The nanoparticles can be stabilized by copolymers such as pluronic� andtheir sizes depend on the concentration of chitosan but are not influenced by theTPP concentration. Calvo et al. [358, 359] have demonstrated the possibility todesign chitosan nanoparticles and chitosan coated with a diblock PEO-PPOcopolymer using this method (Fig. 2.15). The authors have shown the modificationof sizes and zeta potential in function of the amount of the copolymer. Aninteresting feature of chitosan nanoparticles obtained from this method is theirability to swell and shrink upon ionic strength or pH variations. Indeed, an increaseof the pH from acidic to basic causes deprotonation of the chitosan glucosamineunits and, as a consequence, a gel shrinking due to the reduction of the intramo-lecular electric repulsions inside the particles [360]. In addition, variation of theionic strength by increasing the concentration of salt (typically KCl) in the med-ium drops the chitosan–TPP interactions which favor the particles swelling or even

Fig. 2.15 Examples of polysaccharides-based nanoparticles prepared by ionic gelation.a Alginate/chitosan nanoparticles (adapted with permission from [357]). b Influence ofcalcium chloride/sodium alginate ratio on alginate/polylysine and alginate/chitosan nanoparticles(Reprinted with permission from [348]). c Chitosan nanoparticles. d Chitosan-coated PEO–PPOdiblock copolymer (adapted with permission from [359])


their complete restructuration. Thus, due to their triggered swelling response uponpH or ionic strength variations, chitosan nanogels are evidently investigated asdrug delivery nanocarriers [361–365].

Finally, ionic gelation is a method that offers the main advantages of a solvent-free and a relative simple preparation of organic nanoparticles but suffers from thehigh diluted conditions which limit the yield of production of particles.

2.3.2.5 Organic Nanoparticles Prepared by Drying Processes

In the past few years, environmental considerations have motivated research on thedevelopment of methods of nanoparticles synthesis avoiding the utilization oforganic solvents. In this aim, supercritical or spray drying processes offer thepossibility to design and prepare nanoparticles without the main drawbacks of thetraditional methods [47, 48, 366–370].

Supercritical Drying

Two procedures have been developed for the production of nanoparticles usingsupercritical fluid. The first one is based on a rapid expansion of a supercriticalsolution and the second one is founded on a rapid expansion of a supercriticalsolution into liquid solvent.

Rapid Expansion of Supercritical Solution

In this method, organic macromolecules are solubilized in a supercritical fluidsolution which subsequently undergoes a rapid expansion through a nozzle intoambient air. Well-dispersed particles can form resulting from a homogeneousnucleation imposed by the high supersaturation conditions combined with therapid pressure reduction [371]. Generally, CO2 is the supercritical fluid used in themajority of studies. A typical experimental apparatus is composed of three units: ahigh pressure stainless steel mixing cell, a syringe pump, and a pre-expansion unit.The polymer is dissolved in a CO2 solution at ambient temperature in the mixingcell. The solution moves in the pre-expansion unit with the help of the syringepump and is heated isobarically to the pre-expansion temperature until it expandsthrough the nozzle at ambient pressure. Poly(heptadecafluorodecyl acrylate) [372]or poly(L-lactic acid) [373] nanoparticles were yet prepared by this technique andit appears that various factors impact the properties of the particles formed such asthe concentration and degree of saturation of the polymer, the processing condi-tions, the molecular mass and the melting point of the polymer, etc. Although themethod is performed without organic solvents and produces a majority of nano-sized particles, the main drawback is the generation of microsized particles oragglomerates. This is due to a coalescence mechanism involved in the free jet. Toovercome this problem, another technology has been developed.

54 J. Allouche

Rapid Expansion of Supercritical Solution into Liquid Solvent

In contrary to the above method, the supercritical solution expands in this case intoa liquid solvent instead of ambient air [374] (Fig. 2.16). The primary nanosizedparticles are not allowed to grow in the expansion jet due to the presence of theliquid solvent. For instance, poly(heptadecafluorodecylacrylate) (PHDFDA) [375]particles were produced using water as the solvent in which were expanded thesupercritical solution and precipitated the polymer. It was shown that the particleformation results from the aggregation of initially formed nanoparticles. In addi-tion, the presence of NaCl in the water phase helps to a better stabilization of thenanoparticles due to an increase in the ionic strength.

Poly(methyl methacrylate) and poly(L-lactic acid) nanomaterials were also syn-thesized by this method using a CO2-cosolvent as the supercritical fluid. The cosolventallows a better solubilization of the polymers in the supercritical solution and thepresence of NaCl in the water solution generates only nanosized particles [376].

However, in spite of the wide spectrum of fluids available (carbon dioxide,n-pentane, ammonia, etc.), the poor solubility of polymers in these supercriticalfluids remains a main drawback of this technology.

Spray-Drying

Spray-drying process has been used in the past few years for the productionof microsized organic particles or to convert nanoparticle suspensions in drypowder mainly for biomedical and pharmaceutical applications especially in drug

Fig. 2.16 Left: Scheme showing the experimental setup of the rapid expansion of supercriticalfluid solution into liquid solvent process. Right: SEM images of PHDFDA nanoparticles obtainedin presence of NaCl and about 5 min after the rapid expansion process. (adapted with permissionfrom [375])


delivery [377–379]. A typical spray-drying process consists in the atomization of aliquid into a spray of fine droplets brought subsequently in contact with a hotdrying gas to evaporate the moisture and to form the solid product which is finallyrecovered via generally a cyclone unit. Spray-drying technology has undergoneconstant evolution in the past years and the synthesis of polymeric nanosizedparticles obtained in a one-step procedure by spray-drying a polymer solution hasemerged recently. For instance, Li et al. [45] described the preparation of differenttypes of polymeric nanoparticles such as Arabic gum, whey protein, polyvinylalcohol, modified starch, and maltodextrin based on a ‘‘nano spray dryer’’, aninnovative new spray-drying technology developed by Büchi� (Fig. 2.17).

Very recently, the group of Lee et al. [46] has used the same technology to producebovine serum albumin nanoparticles. In contrary to conventional spray dryer, the ‘‘nanospray dryer’’ is characterized by a vibration mesh spray technology creating tiny dropletsin a range of a smaller order of magnitude than the conventional apparatus. The gen-eration of droplets is based on a piezoelectric actuator driven at an ultrasonic frequency(i.e., 60 kHz) ensuring vibration of a thin perforated membrane with micron-sized holeswhich can vary from 4 to 7 lm in diameter. The membrane vibration causes ejection ofmillions of nanodroplets per second with a very narrow size distribution. The final sizesand standard deviation of the nanoparticles obtained depend on several parameters suchas the nature and concentration of the polymer, the spray mesh size, the operatingconditions (drying temperature, feed rate, drying gas flow rate, etc.), or the concentrationof surfactant, if present in the formulation. Finally, another advantage of this noveltechnology is the high yield production of particles that can be in 70–95 % range.

Fig. 2.17 Scheme of the nano Spray-Dryer B-90 (reprinted with permission from [45])

56 J. Allouche

2.4 Conclusion

This chapter provides an overview of the main synthesis methods of organic andbioorganic nanoparticles reported in the literature. Two approaches are highlightedbased on either one- or two-step procedures. In the case of two-step procedures, ananoemulsification step is required prior to conversion of nanodroplets intonanoparticles. It constitutes an important part of the challenge to obtain materialswith well-defined structures and morphologies. High-energy emulsifications are byfar the most widely used methods but low-energy emulsifications, still fewreported, are undergoing a great expansion due to their main advantage in terms ofenvironmental impact. Conversion of nanoemulsions into nanoparticles can bedone subsequently in the second step through several ways including nanogelation,solvent removal, salting out, or polymerization.

In the case of one-step procedures, no nanoemulsification is required and thenanoparticles can be generated via different mechanisms such as nanoprecipita-tion, desolvation, self-assembly, nanogelation, or using more technological wayssuch as supercritical drying or nanospray-drying methods.

In the field of organic nanoparticles, according to the synthesis methodsdescribed above, the control of size, morphology, and structure of particles is stillsubmitted to a number of difficulties that have to be overcome to develop newfunctional nanomaterials based on organic nanoparticles in the future. A betterfundamental knowledge of the processes and mechanisms controlling the particlessynthesis should be the subject of an intensive research in the next decades. Bothtechnological aspects and precipitation techniques in solution should be developedand improved simultaneously to ensure a wide spectrum of preparation methodseasily adapted to a large and increasing range of organic materials available.

References

1. Kreuter J (1994) Nanoparticles. In: Kreuter J (ed) Colloidal drug delivery systems. MarcelDekker Inc, New York, pp 219–342

2. Couvreur P (1988) Polyalkylcyanoacrylates as colloidal drug carriers. Crit Rev Ther DrugCarr Syst 5:1–20

3. Schmid G (2004) Nanoparticles: from theory to application. Wiley-VCH Publisher, Weinheim4. Geckeler KE, Nishide H (2010) Advanced nanomaterials. Wiley-VCH Publishers, Weinheim5. Geckeler KE, Rosenberg E (2006) Functional nanomaterials. American Scientific

Publishers, Valencia6. Hosokawa M, Nogi K, Naito M, Yokoyama T (2007) Nanoparticle technology handbook.

Elsevier, Amsterdam7. Grimsdale AC, Chan KL, Martin RE, Jokisz PG, Holmes AB (2009) Synthesis of light-

emitting conjugated polymers for applications in electroluminescent devices. Chem Rev109:897–1091

8. Müllen K, Scherf U (2006) Organic light-emitting devices. Wiley-VCH Publisher, Weinheim9. Nalwa HS, Rohwer LS (eds) (2003) Handbook of luminescence, display materials, and

devices. American Scientific Publishers, Stevenson Ranch


10. Hadziioannou G, Malliaras GG (eds) (2000) Semiconducting polymers. Wiley-VCHPublisher, Weinheim

11. Couvreur P, Vauthier C (2006) Nanotechnology: intelligent design to treat complex disease.Pharm Res 23:1417–1450

12. Pinto Reis C, Neufeld RJ, Ribeiro AJ, Veiga F (2006) Nanoencapsulation I. Methods forpreparation of drug-loaded polymeric nanoparticles. Nanomed Nanotechnol Biol Med 2: 8–21

13. Pinto Reis C, Neufeld R J, Ribeiro A J, Veiga F (2006) Nanoencapsulation II. Biomedicalapplications and current status of peptide and protein nanoparticulate delivery systems.Nanomed Nanotechnol Biol Med 2:53–65

14. Rao JP, Geckeler KE (2011) Polymer nanoparticles: preparation techniques and size-controlparameters. Prog Polym Sci 36:887–913

15. Pecher J, Mecking S (2010) Nanoparticles of conjugated polymers. Chem Rev 110:6260–6279

16. Anton N, Benoit J-P, Saulnier P (2008) Design and production of nanoparticles formulatedfrom nano-emulsion templates–A review. J Controlled Release 128:185–199

17. Vauthier C, Bouchemal K (2009) Methods for the preparation and manufacture ofpolymeric nanoparticles. Pharm Res 26:1025–1058

18. Landfester K, Musyanovych A, Mailänder V (2010) From polymeric particles tomultifunctional nanocapsules for biomedical applications using the miniemulsion process.J Polym Sci A Polym Chem 48:493–515

19. Allemann E, Gurny R, Doelker E (1993) Drug-loaded nanoparticles—Preparation methodsand drug targeting issues. Eur J Pharm Biopharm 39:173–191

20. Quintanar-Guerrero D, Alle?mann E, Fessi H, Doelker E (1998) Preparation techniques andmechanisms of formation of biodegradable nanoparticles from preformed polymers. DrugDev Ind Pharm 24:1113–1128

21. De Jaeghere F, Doelker E, Gurny R (1999) Nanoparticles, In: Mathiowitz E (ed)Encyclopedia of controlled drug delivery, vol 2. Wiley-VCH, New York, pp 641–664

22. Couvreur P, Barratt G, Fattal E, Legrand P, Vauthier C (2002) Nanocapsule technology:a review. Crit Rev Ther Drug 19:99–134

23. Tuncel D, Demir HV (2010) Conjugated polymer nanoparticles. Nanoscale 2:484–49424. Gangopadhyay R, Conducting Polymer Nanostructures, In: Nalwa H S (ed) (2004)

Encyclopedia of nanoscience and nanotechnology, vol 2. American Scientific Publishers,Stevenson Ranch, pp 105–131

25. Wallace GG, Innis PC (2002) Inherently conducting polymer nanostructures. J NanosciNanotechnol 2:441–451

26. Stejskal J (2001) Colloidal dispersions of conducting polymers. J Polym Mater 18:225–25827. Vincent B (1995) Electrically conducting polymer colloids and composites. Polym Adv

Technol 6:356–36128. Armes SP (1995) Electrically conducting polymer colloids. Polym News 20:233–23729. Aldissi M, Armes SP (1991) Colloidal dispersions of conducting polymers. Prog Org Coat

19:21–5830. Armes SP, Vincent B (1988) Post-doping of sterically-stabilized polyacetylene latexes.

Synth Met 25:171–17931. Groenendaal L, Jonas F, Freitag D, Pielartzik H, Reynolds JR (2000) Poly(3,4-

ethylenedioxythiophene) and its derivatives: past, present, and future. Adv Mater 12:481–49432. Huyal IO, Ozel T, Tuncel D, Demir HV (2008) Quantum efficiency enhancement in film by

making nanoparticles of polyfluorene. Opt Express 16:13391–1339733. Ozel IO, Ozel T, Demir HV, Tuncel D (2010) Non-radiative resonance energy transfer in

bi-polymer nanoparticles of fluorescent conjugated polymers. Opt Express 18:670–68434. Grigalevicius S, Forster M, Ellinger S, Landfester K, Scherf U (2006) Excitation energy

transfer from semi-conducting polymer nanoparticles to surface-bound fluorescent dyes.Macromol Rapid Commun 27:200–202

35. Pecher J, Mecking S (2007) Nanoparticles from step-growth coordination polymerization.Macromolecules 40:7733–7735

58 J. Allouche

36. Pecher J, Mecking S (2008) Poly(p-phenylene vinylene) nanoparticles by acyclic dienemetathesis (ADMET) polycondensation in aqueous emulsion. Polymer Preprints (AmericanChemical Society, division of Polymer Chemistry), pp 363–364

37. Rahim NAA, McDaniel W, Bardon K, Srinivasan S, Vickerman V, So PTC, Moon JH(2009) Conjugated polymer nanoparticles for two-photon imaging of endothelial cells in atissue model. Adv Mater 21:3492–3496

38. Hittinger E, Kokil A, Weder C (2004) Synthesis and characterization of cross-linkedconjugated polymer milli-, micro-, and nanoparticles. Angew Chem Int Ed 43:1808–1811

39. Müller RH, Mäder K, Gohla S (2000) Solid lipid nanoparticles (SLN) for controlled drugdelivery—A review of the state of the art. Eur J Pharm Biopharm 50:161–177

40. Pragati S, Kuldeep S, Ashok S, Satheesh M (2009) Solid lipid nanoparticles: a promisingdrug delivery technology. Int J Pharm Sci Nanotechnol 2:509–516

41. Basu B, Garala K, Bhalodia R, Joshi B, Mehta K (2010) Solid lipid nanoparticles:apromising tool for drug delivery system. J Pharm Res 3:84–92

42. Freitas C, Müller RH (1999) Correlation between long-term stability of solid lipidnanoparticles (SLN(TM)) and crystallinity of the lipid phase. Eur J Pharm Biopharm47:125–132

43. Müller RH, Radtke M, Wissing SA (2002) Nanostructured lipid matrices for improvedmicroencapsulation of drugs. Int J Pharm 242:121–128

44. Olbrich C, Gessner A, Kayser O, Müller RH (2002) Lipid-drug-conjugate (LDC)nanoparticles as novel carrier system for the hydrophilic antitrypanosomal drugdiminazenediaceturate. J Drug Targeting 10:387–396

45. Li X, Anton N, Arpagaus C, Belleteix F, Vandamme TF (2010) Nanoparticles by spraydrying using innovative new technology: the Büchi Nano spray dryer B-90. J ControlledRelease 147:304–310

46. Lee SH, Heng D, Ng WK, Chan H-K, Tan RBH (2011) Nano spray drying: a novel methodfor preparing protein nanoparticles for protein therapy. Int J Pharm 403:192–200

47. York P (1999) Strategies for particle design using supercritical fluid technologies. PharmSci Technol Today 2:430–440

48. Shariati A, Peters CJ (2003) Recent developments in particle design using supercriticalfluids. Curr Opin Solid State Mater Sci 7:371–383

49. Wright IK, Higginbotham A, Baker SM, Donnelly TD (2010) Generation of nanoparticlesof controlled size using ultrasonic piezoelectric oscillators in solution. ACS Appl MaterInterfaces 2:2360–2364

50. Becher P (1965) Emulsions: theory and practice. Reinhold Pub Corp, New York51. Becher P (1985) Encyclopedia of emulsion technology. Marcel Dekker Inc, New York52. Mittal KL, Lindman B (eds) (1984) Surfactants in solution. Plenum, New York53. Ruschak KJ, Miller CA (1972) Spontaneous emulsification in ternary systems with mass

transfer. Ind Eng Chem Fundam 11:534–54054. Miller CA (1988) Spontaneous emulsification produced by diffusion—a review. Colloids

Surf 29:89–10255. El-Aasser MS, Lack CD, Vanderhoff JW, Fowkes FM (1988) The miniemulsification

process—different form of spontaneous emulsification. Colloids Surf 29:103–11856. Ganachaud F, Katz JL (2005) Nanoparticles and nanocapsules created using the Ouzo

effect: spontaneous emulsification as an alternative to ultrasonic and high-shear devices.ChemPhysChem 6:209–216

57. Bouchemal K, Briançon S, Perrier E, Fessi H (2004) Nano-emulsion formulation usingspontaneous emulsification: solvent, oil and surfactant optimization. Int J Pharm 280:241–251

58. Kawashima Y, Yamamoto H, Takeuchi H, Hino T, Niwa T (1998) Properties of a peptidecontaining DL-lactide/glycolide copolymer nanospheres prepared by novel emulsionsolvent diffusion methods. Eur J Pharm Biopharm 45:41–48

59. Quintanar-Guerrero D, Allémann E, Doelker E, Fessi H (1997) A mechanistic study of theformation of polymer nanoparticles by the emulsification-diffusion technique. ColloidPolym Sci 275:640–647


60. Quintanar-Guerrero D, Allémann E, Fessi H, Doelker E (1999) Pseudolatex preparationusing a novel emulsion-diffusion process involving direct displacement of partially water-miscible solvents by distillation. Int J Pharm 188:155–164

61. Quintanar-Guerrero D, Allémann E, Doelker E, Fessi H (1998) Preparation andcharacterization of nanocapsnles from preformed polymers by a new process based onemulsification-diffusion technique. Pharm Res 15:1056–1062

62. Gallardo M, Couarraze G, Denizot B, Treupel L, Couvreur P, Puisieux F (1993) Study of themechanisms of formation of nanoparticles and nanocapsules of polyisobutyl-2-cyanoacrylate. Int J Pharm 100:55–64

63. Fessi H, Puisieux F, Devissaguet JP, Ammoury N, Benita S (1989) Nanocapsule formationby interfacial polymer deposition following solvent deplacement. Int J Pharm 55:25–28

64. Ostrovsky MV, Good RJ (1984) Mechanism of microemulsion formation in systems withlow interfacial tension: occurrence, properties, and behavior of microemulsions. J ColloidInterface Sci 102:206–226

65. Marszall L, Shick MJ (eds) (1987) Nonionic surfactants, surfactant sciences series, vol 23.Marcel Dekker Inc, New York

66. Taylor P, Ottewill RH (1994) The formation and ageing rates of oil-in-water miniemulsions.Colloids Surf A 88:303–316

67. Taylor P, Ottewill RH (1994) Ostwald ripening in O/W miniemulsions formed by thedilution of O/W microemulsions. Prog Colloid Polym Sci 97:199–203

68. Forgiarini A, Esquena J, González C, Solans C (2001) Formation of nano-emulsions by low-energy emulsification methods at constant temperature. Langmuir 17:2076–2083

69. Wu H, Ramachandran C, Weiner ND, Roessler BJ (2001) Topical transport of hydrophiliccompounds using water-in-oil nanoemulsions. Int J Pharm 220:63–75

70. Porras M, Solans C, González C, Martínez A, Guinart A, Gutiérrez JM (2004) Studies offormation of W/O nano-emulsions. Colloids Surf A 249:115–118

71. Usón N, Garcia MJ, Solans C (2004) Formation of water-in-oil (W/O) nano-emulsions in awater/mixed non-ionic surfactant/oil systems prepared by a low-energy emulsificationmethod. Colloids Surf A 250:415–421

72. Solè I, Maestro A, Pey CM, González C, Solans C, Gutiérrez JM (2006) Nano-emulsionspreparation by low energy methods in an ionic surfactant system. Colloids Surf A 288:138–143

73. Solè I, Maestro A, González C, Solans C, Gutiérrez JM (2006) Optimization of nano-emulsionpreparation by low-energy methods in an ionic surfactant system. Langmuir 22:8326–8332

74. Shinoda K, Saito H (1968) The effect of temperature on the phase equilibria and the types ofdispersions of the ternary system composed of water, cyclohexane, and nonionic surfactant.J Colloid Interface Sci 26:70–74

75. Shinoda K, Saito H (1969) The stability of O/W type emulsions as functions of temperatureand the HLB of emulsifiers: the emulsification by PIT-method. J Colloid Interface Sci30:258–263

76. Izquierdo P, Esquena J, Tadros TF, Dederen C, Garcia MJ, Azemar N, Solans C (2002)Formation and stability of nano-emulsions prepared using the phase inversion temperaturemethod. Langmuir 18:26–30

77. Izquierdo P, Esquena J, Tadros TF, Dederen JC, Feng J, Garcia-Celma MJ, Azemar N,Solans C (2004) Phase behavior and nano-emulsion formation by the phase inversiontemperature method. Langmuir 20:6594–6598

78. Solans C, Izquierdo P, Nolla J, Azemar N, Garcia-Celma MJ (2005) Nano-emulsions. CurrOpin Colloid Interface Sci 10:102–110

79. Förster T, Von Rybinski W, Wadle A (1995) Influence of microemulsion phases on thepreparation of fine-disperse emulsions. Adv Colloid Interface Sci 58:119–149

80. Pons R, Carrera I, Caelles J, Rouch J, Panizza P (2003) Formation and properties ofminiemulsions formed by microemulsions dilution. Adv Colloid Interface Sci 106:129–146

81. Anton N, Gayet P, Benoit J-P, Saulnier P (2007) Nano-emulsions and nanocapsules by thePIT method: an investigation on the role of the temperature cycling on the emulsion phaseinversion. Int J Pharm 344:44–52

60 J. Allouche

82. Salager J-L, Marquez N, Graciaa A, Lachaise J (2000) Partitioning of ethoxylatedoctylphenol surfactants in microemulsion–oil–water systems: influence of temperature andrelation between partitioning coefficient and physicochemical formulation. Langmuir16:5534–5539

83. Salager JL, Antón RE, Andérez JM, Aubry JM (2001) Formulation des micro-émulsions parla méthode HLD, Techniques De L’Ingénieur, Génie Des Procédés J2: 1–20

84. Salager JL (1999) Microemulsions, handbook of detergents—part A: properties. MarcelDekker Inc, New York, pp 253–302

85. Salager JL (2000) Pharmaceutical emulsions and suspensions, formulation concepts for theemulsion maker. Marcel Dekker Inc, New York, pp 19–72

86. Bourrel M, Salager JL, Schechter RS, Wade WH (1980) A correlation for phase behavior ofnonionic surfactants. J Colloid Interface Sci 75:451–461

87. Rondón-González M, Sadtler V, Choplin L, Salager J-L (2006) Emulsion inversion fromabnormal to normal morphology by continuous stirring without internal phase addition.Effect of surfactant mixture fractionation at extreme water-oil ratio. Colloids Surf A288:151–157

88. Rondón-Gonzaléz M, Sadtler V, Choplin L, Salager J-L (2006) Emulsion catastrophicinversion from abnormal to normal morphology. 5. Effect of the water-to-oil ratio andsurfactant concentration on the inversion produced by continuous stirring. Ind Eng ChemRes 45:3074–3080

89. Tyrode E, Allouche J, Choplin L, Salager J-L (2005) Emulsion catastrophic inversion fromabnormal to normal morphology. 4. Following the emulsion viscosity during three inversionprotocols and extending the critical dispersed-phase concept. Ind Eng Chem Res 44:67–74

90. Tyrode E, Mira I, Zambrano N, Márquez L, Rondón-Gonzalez M, Salager J-L (2003)Emulsion catastrophic inversion from abnormal to normal morphology. 3. Conditions fortriggering the dynamic inversion and application to industrial processes. Ind Eng Chem Res42:4311–4318

91. Salager J-L, Forgiarini A, Márquez L, Peña A, Pizzino A, Rodriguez MP, Rondón-GonzálezM (2004) Using emulsion inversion in industrial processes. Adv Colloid Interface Sci108–109:259–272

92. Allouche J, Tyrode E, Sadtler V, Choplin L, Salager J-L (2004) Simultaneous conductivityand viscosity measurements as a technique to track emulsion inversion by the phase-inversion-temperature method. Langmuir 20:2134–2140

93. Salager J-L, Marquez L, Pena AA, Rondon M, Silva F, Tyrode E (2000) Currentphenomenological know-how and modeling of emulsion inversion. Ind Eng Chem Res39:2665–2676

94. Salager J-L (1996) Guidelines for the formulation, composition and stirring to attain desiredemulsion properties (type, droplet size, viscosity and stability), Surfactant Science Series,pp 261–295

95. Marquez L, Graciaa A, Lachaise J, Salager J-L, Zambrano N (2003) Hysteresis behavior intemperature-induced emulsion inversion. Polym Int 52:590–593

96. Pizzino A, Rodriguez MP, Xuereb C, Catte M, Van HE, Aubry J-M, Salager J-L (2007)Light backscattering as an indirect method for detecting emulsion inversion. Langmuir23:5286–5288

97. Stork M, Tousain RL, Wieringa JA, Bosgra OH (2003) A MILP approach to theoptimization of the operation procedure of a fed-batch emulsification process in a stirredvessel. Comput Chem Eng 27:1681–1691

98. Mabille C, Leal-Calderon F, Bibette J, Schmitt V (2003) Monodisperse fragmentation inemulsions: mechanisms and kinetics. Europhys Lett 61:708–714

99. Mabille C, Schmitt V, Gorria P, Calderon FL, Faye V, Deminiere B, Bibette J (2000)Rheological and shearing conditions for the preparation of monodisperse emulsions.Langmuir 16:422–429

100. Trotta M, Pattarino F, Ignoni T (2002) Stability of drug-carrier emulsions containingphosphatidylcholine mixtures. Eur J Pharm Biopharm 53:203–208


101. Lizarraga MS, Pan LG, Anon MC, Santiago LG (2008) Stability of concentrated emulsionsmeasured by optical and rheological methods. Effect of processing conditions-I. Wheyprotein concentrate. Food Hydrocoll 22:868–878

102. Bengoechea C, Cordobes F, Puppo MC, Guerrero A (2007) Linear viscoelasticity and dropletsize distribution of O/W emulsions stabilized by plant proteins. Afinidad 64:696–704

103. Higgins DM, Skauen DM (1972) Influence of power on quality of emulsions prepared byultrasound. J Pharm Sci 61:1567–1570

104. Li MK, Fogler HS (1978) Acoustic emulsification—1. The instability of the oil–waterinterface to form the initial droplets. J Fluid Mech 88:499–511

105. Li MK, Fogler HS (1978) Acoustic emulsification—2 breakup of the large primary oildroplets in water medium. J Fluid Mech 88:513–528

106. Griffin WC (1979) Emulsions. In: Kirk-Othmer (ed) Encyclopedia of Chemical Technology,vol 8. Wiley, Weinheim, pp 900–930

107. Johnson JC (1979) Emulsifiers and emulsifying techniques. Noyes Data Corp, Park Ridge108. Reddy SR, Fogler HS (1980) Emulsion stability of acoustically formed emulsions. J Phys

Chem 84:1570–1575109. Eberth K, Merry J (1983) A comparative study of emulsions prepared by ultrasound and by

a conventional method. Droplet size measurements by means of a Coulter Counter andmicroscopy. Int J Pharm 14:349–353

110. Walstra P (1993) Principles of emulsion formation. Chem Eng Sci 48:333–349111. Abismail B, Canselier JP, Wilhelm AM, Delmas H, Gourdon C (1999) Emulsification by

ultrasound: drop size distribution and stability. Ultrason Sonochem 6:75–83112. Mongenot N, Charrier S, Chalier P (2000) Effect of ultrasound emulsification on cheese

aroma encapsulation by carbohydrates. J Agric Food Chem 48:861–867113. Corzo-Martinez M, Soria AC, Villamiel M, Olano A, Harte FM, Moreno FJ (2011) Effect of

glycation on sodium caseinate-stabilized emulsions obtained by ultrasound. J Dairy Sci94:51–58

114. Wood RW, Loomis AL (1927) The physical and biological effects of high frequency soundwaves of great intensity. Philos Mag 4:417–436

115. Akiyoshi K, Kang E-C, Kurumada S, Sunamoto J, Principi T, Winnik FM (2000) Controlledassociation of amphiphilic polymers in water: thermosensitive nanoparticles formed by self-assembly of hydrophobically modified pullulans and poly(n-isopropylacrylamides).Macromolecules 33:3244–3249

116. Xia H, Wang Q (2001) Synthesis and characterization of conductive polyaniline nanoparticlesthrough ultrasonic assisted inverse microemulsion polymerization. J Nanopart Res 3:401–411

117. Xia H, Zhang C, Wang Q (2001) Study on ultrasonic induced encapsulating emulsionpolymerization in the presence of nanoparticles. J Appl Polym Sci 80:1130–1139

118. Hou D, Xie C, Huang K, Zhu C (2003) The production and characteristics of solid lipidnanoparticles (SLNs). Biomaterials 24:1781–1785

119. Li Y, Dong L, Jia A, Chang X, Xue H (2006) Preparation and characterization of solid lipidnanoparticles loaded traditional chinese medicine. Int J Biol Macromol 38:296–299

120. Luo Y, Chen D, Ren L, Zhao X, Qin J (2006) Solid lipid nanoparticles for enhancingvinpocetine’s oral bioavailability. J Controlled Release 114:53–59

121. Wong HL, Bendayan R, Rauth AM, Xue HY, Babakhanian K, Wu XY (2006) Amechanistic study of enhanced doxorubicin uptake and retention in multidrug resistantbreast cancer cells using a polymer–lipid hybrid nanoparticle system. J Pharmacol Exp Ther317:1372–1381

122. Yegin BA, Benoit J-P, Lamprecht A (2006) Paclitaxel-loaded lipid nanoparticles preparedby solvent injection or ultrasound emulsification. Drug Dev Ind Pharm 32:1089–1094

123. Sharma P, Ganta S, Denny WA, Garg S (2009) Formulation and pharmacokinetics of lipidnanoparticles of a chemically sensitive nitrogen mustard derivative: chlorambucil. Int JPharm 367:187–194

124. Lee KJ, Oh W-K, Song J, Kim S, Lee J, Jang J (2010) Photoluminescent polymernanoparticles for label-free cellular imaging. Chem Commun 46:5229–5231

62 J. Allouche

125. Aji A, Chacko AJ, Jose S, Souto EB (2011) Lopinavir loaded solid lipid nanoparticles(SLN) for intestinal lymphatic targeting. Eur J Pharm Sci 42:11–18

126. Das S, Ng WK, Kanaujia P, Kim S, Tan RBH (2011) Formulation design, preparation andphysicochemical characterizations of solid lipid nanoparticles containing a hydrophobicdrug: effects of process variables. Colloids Surf B 88:483–489

127. Allouche J, Boissiere M, Helary C, Livage J, Coradin T (2006) Biomimetic core-shellgelatine/silica nanoparticles: a new example of biopolymer-based nanocomposites. J MaterChem 16:3120–3125

128. Makino K, Mossoba MM, Riesz P (1982) Chemical effects of ultrasound on aqueoussolutions. Evidence for hydroxyl and hydrogen free radicals (.cntdot.OH and.cntdot.H) byspin trapping. J Am Chem Soc 104:3537–3539

129. Makino K, Mossoba MM, Riesz P (1983) Chemical effects of ultrasound on aqueoussolutions. Formation of hydroxyl radicals and hydrogen atoms. J Phys Chem 87:1369–1377

130. Seo M, Nie Z, Xu S, Mok M, Lewis PC, Graham R, Kumacheva E (2005) Continuousmicrofluidic reactors for polymer particles. Langmuir 21:11614–11622

131. Atencia J, Beebe DJ (2005) Controlled microfluidic interfaces. Nature 437:648–655132. Nisisako T, Okushima S, Torii T (2005) Controlled formulation of monodisperse double

emulsions in a multiple-phase microfluidic system. Soft Matter 1:23–27133. Jahn A, Reiner JE, Vreeland WN, DeVoe DL, Locascio LE, Gaitan M (2008) Preparation of

nanoparticles by continuous-flow microfluidics. J Nanopart Res 10:925–934134. Engl W, Backov R, Panizza P (2008) Controlled production of emulsions and particles by

milli- and microfluidic techniques. Curr Opin Colloid Interface Sci 13:206–216135. Kumacheva E, Zhang H, Nie Z (2009) Polymerization in microfluidic reactors. In:

Microchemical engineering in practice , pp. 361–383 John Wiley and Sons Inc., Weinheim,Germany

136. Schaerli Y, Hollfelder F (2009) The potential of microfluidic water-in-oil droplets inexperimental biology. Mol BioSyst 5:1392–1404

137. Zhao C-X, Middelberg APJ (2011) Two-phase microfluidic flows. Chem Eng Sci 66:1394–1411

138. Zhao C-X, He L, Qiao SZ, Middelberg APJ (2011) Nanoparticle synthesis in microreactors.Chem Eng Sci 66:1463–1479

139. Karnik R, Gu F, Basto P, Cannizzaro C, Dean L, Kyei-Manu W, Langer R, Farokhzad OC(2008) Microfluidic platform for controlled synthesis of polymeric nanoparticles. Nano Lett8:2906–2912

140. Charcosset C, Fessi H (2005) Preparation of nanoparticles with a membrane contactor.J Membr Sci 266:115–120

141. Rondeau E, Cooper-White JJ (2008) Biopolymer microparticle and nanoparticle formationwithin a microfluidic device. Langmuir 24:6937–6945

142. Gurny R, Peppas NA, Harrington DD, Banker GS (1981) Development of biodegradableand injectable latices for controlled release of potent drugs. Drug Dev Ind Pharm 7:1–25

143. Quintanar-Guerrero D, Allémann E, Fessi H, Doelker E (1999) Pseudolatex preparationusing a novel emulsion-diffusion process involving direct displacement of partially water-miscible solvents by distillation. Int J Pharm 188:155–164

144. Choonara YE, PillayV, NdesendoVMK, duToit LC,KumarP, KhanRA, MurphyCS, Jarvis D-L(2011) Polymeric emulsion and crosslink-mediated synthesis of super-stable nanoparticles assustained-release anti-tuberculosis drug carriers. Colloids Surf B 87:243–254

145. Lee W-K, Park J-Y, Jung S, Chul WY, Kim W-U, Kim H-Y, Park J-H, Park J-S (2005)Preparation and characterization of biodegradable nanoparticles entrapping immunodominantpeptide conjugated with PEG for oral tolerance induction. J Controlled Release 105:77–88

146. Venier-Julienne MC, Benoît JP (1996) Preparation, purification and morphology ofpolymeric nanoparticles as drug carriers. Pharm Acta Helv 71:121–128

147. Song CX, Labhasetwar V, Murphy H, Qu X, Humphrey WR, Shebuski RJ, Levy RJ (1997)Formulation and characterization of biodegradable nanoparticles for intravascular local drugdelivery. J Controlled Release 43:197–212


148. Zambaux MF, Bonneaux F, Gref R, Maincent P, Dellacherie E, Alonso MJ, Labrude P,Vigneron C (1998) Influence of experimental parameters on the characteristics of poly(lacticacid) nanoparticles prepared by a double emulsion method. J Controlled Release 50:31–40

149. Bazile DV, Ropert C, Huve P, Verrecchia T, Marland M, Frydman A, Veillard M,Spenleuhauer G (1992) Body distribution of fully biodegradable [14C]-poly(lactic acid)nanoparticles coated with albumin after parenteral administration to rats. Biomaterials13:1093–1102

150. Singh J, Pandit S, Bramwell VW, Alpar HO (2006) Diphtheria toxoid loaded poly-([epsilon]-caprolactone) nanoparticles as mucosal vaccine delivery systems. Methods 38:96–105

151. Quellec P, Gref R, Dellacherie E, Sommer F, Tran MD, Alonso MJ (1999) Proteinencapsulation within poly(ethylene glycol)-coated nanospheres. II. Controlled releaseproperties. J Biomed Mater Res 47:388–395

152. Bazile D, Prud’Homme C, Bassoullet M-T, Marlard M, Spenlehauer G, Veillard M (1995)Stealth Me.PEG-PLA nanoparticles avoid uptake by the mononuclear phagocytes system.J Pharm Sci 84:493–498

153. Luo G, Yu X, Jin C, Yang F, Fu D, Long J, Xu J, Zhan C, Lu W (2010) LyP-1-conjugatednanoparticles for targeting drug delivery to lymphatic metastatic tumors. Int J Pharm385:150–156

154. Lemarchand C, Couvreur P, Vauthier C, Costantini D, Gref R (2003) Study of emulsionstabilization by graft copolymers using the optical analyzer Turbiscan. Int J Pharm 254:77–82

155. Lemarchand C, Couvreur P, Besnard M, Costantini D, Gref R (2003) Novel polyester-polysaccharide nanoparticles. Pharm Res 20:1284–1292

156. Moinard-Checot D, Chevalier Y, Briançon S, Fessi H, Guinebretière S (2006) Nanoparticlesfor drug delivery: review of the formulation and process difficulties illustrated by theemulsion–diffusion process. J Nanosci Nanotechnol 6:2664–2681

157. Moinard-Chécot D, Chevalier Y, Briançon S, Beney L, Fessi H (2008) Mechanism ofnanocapsules formation by the emulsion–diffusion process. J Colloid Interface Sci 317:458–468

158. Leroux J-C, Allemann E, Doelker E, Gurny R (1995) New approach for the preparation ofnanoparticles by an emulsification-diffusion method. Eur J Pharm Biopharm 41:14–18

159. Quintanar-Guerrero D, Tamayo-Esquivel D, Ganem-Quintanar A, Allémann E, Doelker E(2005) Adaptation and optimization of the emulsification-diffusion technique to preparelipidic nanospheres. Eur J Pham Sci 26:211–218

160. Quintanar-Guerrero D, Fessi H, Allémann E, Doelker E (1996) Influence of stabilizingagents and preparative variables on the formation of poly(D,L-lactic acid) nanoparticles byan emulsification-diffusion technique. Int J Pharm 143:133–141

161. Trimaille T, Pichot C, Ela A, Fessi H, Briançon S, Delair T (2003) Poly(D,L-lactic acid)nanoparticle preparation and colloidal characterization. Colloid Polym Sci 281:1184–1190

162. Choi S-W, Kwon H-Y, Kim W-S, Kim J-H (2002) Thermodynamic parameters on poly(d,l-lactide-co-glycolide) particle size in emulsification-diffusion process. Colloids Surf A201:283–289

163. Kwon H-Y, Lee J-Y, Choi S-W, Jang Y, Kim J-H (2001) Preparation of PLGA nanoparticlescontaining estrogen by emulsification-diffusion method. Colloids Surf A 182:123–130

164. Swarnakar NK, Jain AK, Singh RP, Godugu C, Das M, Jain S (2011) Oral bioavailability,therapeutic efficacy and reactive oxygen species scavenging properties of coenzyme Q10-loaded polymeric nanoparticles. Biomaterials 32:6860–6874

165. El-Shabouri MH (2002) Positively charged nanoparticles for improving the oralbioavailability of cyclosporin-A. Int J Pharm 249:101–108

166. Yan C, Chen D, Gu J, Qin J (2006) Nanoparticles of 5-fluorouracil (5-FU) loadedN-succinyl-chitosan (Suc-Chi) for cancer chemotherapy: preparation, characterization—invitro drug release and anti-tumour activity. J Pharm Pharmacol 58:1177–1181

167. Yan C, Gu J, Yan C, Zhan H, Chen D (2010) In vivo biodistribution for tumor targeting of5-fluorouracil (5-FU) loaded N-succinyl-chitosan (Suc-Chi) nanoparticles. BioChem IndianJ 4:21–25

64 J. Allouche

168. Ibrahim H, Bindschaedler C, Doelker E, Buri P, Gurny R (1992) Aqueous nanodispersionsprepared by a salting-out process. Int J Pharm 87:239–246

169. De Jaeghere F, Allémann E, Leroux J-C, Stevels W, Feijen J, Doelker E, Gurny R (1999)Formulation and lyoprotection of poly(Lactic acid-co-ethylene oxide) nanoparticles:influence on physical stability and in vitro cell uptake. Pharm Res 16:859–866

170. Nguyen CA, Allémann E, Schwach G, Doelker E, Gurny R (2003) Synthesis of a novelfluorescent poly(D,L-lactide) end-capped with 1-pyrenebutanol used for the preparation ofnanoparticles. Eur J Pham Sci 20:217–222

171. Zweers MLT, Engbers GHM, Grijpma DW, Feijen J (2004) In vitro degradation ofnanoparticles prepared from polymers based on DL-lactide, glycolide and poly(ethyleneoxide). J Controlled Release 100:347–356

172. Perugini P, Simeoni S, Scalia S, Genta I, Modena T, Conti B, Pavanetto F (2002) Effect ofnanoparticle encapsulation on the photostability of the sunscreen agent, 2-ethylhexyl-p-methoxycinnamate. Int J Pharm 246:37–45

173. Allemann E, Gurny R, Doelker E (1992) Preparation of aqueous polymeric nanodispersionsby a reversible salting-out process: Influence of process parameters on particle size. Int JPharm 87:247–253

174. Konan YN, Gurny R, Allémann E (2002) Preparation and characterization of sterile andfreeze-dried sub-200 nm nanoparticles. Int J Pharm 233:239–252

175. Galindo-Rodriguez S, Allémann E, Fessi H, Doelker E (2004) Physicochemical parametersassociated with nanoparticle formation in the salting-out, emulsification-diffusion, andnanoprecipitation methods. Pharm Res 21:1428–1439

176. Reis CP, Neufeld RJ, Vilela S, Ribeiro AJ, Veiga F (2006) Review and current status ofemulsion/dispersion technology using an internal gelation process for the design of alginateparticles. J Microencapsul 23:245–257

177. Wang N, Wu XS (1997) Preparation and characterization of agarose hydrogel nanoparticlesfor protein and peptide drug delivery. Pharm Dev Technol 2:135–142

178. Reis CP, Neufeld RJ, Ribeiro AJ, Veiga F (2006) Design of insulin-loaded alginatenanoparticles: influence of the calcium ion on polymer gel matrix properties. Chem IndChem Eng Q 12:47–52

179. Arshady R (1988) Preparation of polymer nano- and microspheres by vinyl polymerizationtechniques. J Microencapsul 5:101–114

180. Asua JM (2002) Miniemulsion polymerization. Prog Polym Sci 27:1283–1346181. Landfester K (2006) Encapsulation through (mini)emulsion polymerization. Functional

coating Wiley-VCH, Weinheim, Germany182. Chern CS (2006) Emulsion polymerization mechanisms and kinetics. Prog Polym Sci

31:443–486183. Thickett SC, Gilbert RG (2007) Emulsion polymerization: state of the art in kinetics and

mechanisms. Polymer 48:6965–6991184. Landfester K (2009) Miniemulsion polymerization and the structure of polymer and hybrid

nanoparticles. Angew Chem Int Ed 48:4488–4507185. Yoon S-J, Chun H, Lee M-S, Kim N (2009) Preparation of poly(N-vinylcarbazole) (PVK)

nanoparticles by emulsion polymerization and PVK hollow particles. Synth Met 159:518–522186. Costa C, Santos AF, Fortuny M, Araújo PHH, Sayer C (2009) Kinetic advantages of using

microwaves in the emulsion polymerization of MMA. Mater Sci Eng C 29:415–419187. Cheng X, Chen M, Zhou S, Wu L (2006) Preparation of SiO2/PMMA composite particles

via conventional emulsion polymerization. J Polym Sci Part A Polym Chem 44:3807–3816188. Muñoz-Bonilla A, Van Herk AM, Heuts JPA (2010) Preparation of hairy particles and

antifouling films using brush-type amphiphilic block copolymer surfactants in emulsionpolymerization. Macromolecules 43:2721–2731

189. Garay-Jimenez JC, Gergeres D, Young A, Lim DV, Turos E (2009) Physical properties andbiological activity of poly(butyl acrylate-styrene) nanoparticle emulsions prepared withconventional and polymerizable surfactants. Nanomed Nanotechnol Biol Med 5: 443–451


190. Lu S, Qu R, Forcada J (2009) Preparation of magnetic polymeric composite nanoparticlesby seeded emulsion polymerization. Mater Lett 63:770–772

191. Gao J, Wu C (2005) Modified structural model for predicting particle size in themicroemulsion and emulsion polymerization of styrene under microwave irradiation.Langmuir 21:782–785

192. Zhang J, Cao Y, He Y (2004) Ultrasonically irradiated emulsion polymerization of styrenein the presence of a polymeric surfactant. J Appl Polym Sci 94:763–768

193. Chang Y-H, Lee Y-D, Karlsson OJ, Sundberg DC (2001) Particle nucleation mechanism forthe emulsion polymerization of styrene with a novel polyester emulsifier. J Appl Polym Sci82:1061–1070

194. Thickett SC, Gaborieau M, Gilbert RG (2007) Extended mechanistic description of particlegrowth in electrosterically stabilized emulsion polymerization systems. Macromolecules40:4710–4720

195. Mock EB, De Bruyn H, Hawkett BS, Gilbert RG, Zukoski CF (2006) Synthesis ofanisotropic nanoparticles by seeded emulsion polymerization. Langmuir 22:4037–4043

196. El-Samaligy MS, Rohdewald P, Mahmoud HA (1986) Polyalkyl cyanoacrylatenanocapsules. J Pharm Pharmacol 38:216–218

197. Couvreur P, Kante B, Roland M (1979) Polycyanoacrylate nanocapsules as potentiallysosomotropic carriers: preparation, morphological and sorptive properties. J PharmPharmacol 31:331–332

198. Vauthier C, Labarre D, Ponchel G (2007) Design aspects of poly(alkylcyanoacrylate)nanoparticles for drug delivery. J Drug Target 15:641–663

199. Nicolas J, Couvreur P (2009) Synthesis of poly(alkyl cyanoacrylate)-based colloidalnanomedicines. Wiley interdisciplinary reviews. Nanomed Nanobiotechnol 1:111–127

200. Bertholon I, Lesieur S, Labarre D, Besnard M, Vauthier C (2006) Characterization ofdextran-poly(isobutylcyanoacrylate) copolymers obtained by redox radical and anionicemulsion polymerization. Macromolecules 39:3559–3567

201. Bertholon I, Ponchel G, Labarre D, Couvreur P, Vauthier C (2006) Bioadhesive propertiesof poly(alkylcyanoacrylate) nanoparticles coated with polysaccharide. J NanosciNanotechnol 6:3102–3109

202. Hearn J, Wilkinson MC, Goodall AR, Chainey M (1985) Kinetics of the surfactant-freeemulsion polymerization of styrene: the post nucleation stage. J Polym Sci Part A PolymChem 23:1869–1883

203. Song Z, Poehlein GW (1990) Kinetics of emulsifier-free emulsion polymerization ofstyrene. J Polym Sci Part A Polym Chem 28:2359–2392

204. Zou D, Ma S, Guan R, Park M, Sun L, Aklonis JJ, Salovey R (1992) Model filled polymers.V. Synthesis of crosslinked monodisperse polymethacrylate beads. J Polym Sci Part APolym Chem 30:137–144

205. Shouldice GTD, Vandezande GA, Rudin A (1994) Practical aspects of the emulsifier-freeemulsion polymerization of styrene. Eur Polym J 30:179–183

206. Pang S-W, Park H-Y, Jang Y-S, Kim W-S, Kim J-H (2002) Effects of charge density andparticle size of poly(styrene/(dimethylamino)ethyl methacrylate) nanoparticle for genedelivery in 293 cells. Colloids Surf B 26:213–222

207. Akgöl S, Öztürk N, Denizli A (2010) New generation polymeric nanospheres for lysozymeadsorption. J Appl Polym Sci 115:1608–1615

208. Liu G, Liu P (2010) Synthesis of monodispersed crosslinked nanoparticles decorated withsurface carboxyl groups via soapless emulsion polymerization. Colloids Surf A 354:377–381

209. Goodall AR, Wilkinson MC, Hearn J (1977) Mechanism of emulsion polymerization ofstyrene in soap-free systems. J Polym Sci Polym Chem Ed 15:2193–2218

210. Landfester K (2001) Polyreactions in miniemulsions. Macromol Rapid Commun 22:896–936211. Fitch R M, Tsai C H (1971) Particle formation in polymer colloids. III. Prediction of the

number of particles by a homogeneous nucleation theory. Polymer Colloids. 73–102

66 J. Allouche

212. Hansen FK, Ugelstad J (1979) Particle nucleation in emulsion polymerization—3 nucleationin systems with anionic emulsifier investigated by seeded and unseeded polymerization.J Polym Sci Part A Polym Chem 17:3047–3067

213. Hansen FK, Ugelstad J (1982) Particle formation mechanisms, In: Piirma I (ed) Emulsionpolymerization. Academic press, New York, pp 51–92

214. Choi YT, El-Aasser MS, Sudol ED, Vanderhoff JW (1985) Polymerization of styreneminiemulsion. J Polym Sci Part A Polym Chem 23:2973–2987

215. Chern CS, Liou YC, Chen TJ (1998) Particle nucleation loci in styrene miniemulsionpolymerization using alkyl methacrylates as the reactive cosurfactant. Macromol ChemPhys 199:1315–1322

216. Chern CS, Chen TJ, Liou YC (1998) Miniemulsion polymerization of styrene in thepresence of a water-insoluble blue dye. Polymer 39:3767–3777

217. Bao J, Zhang A (2004) Poly(methyl methacrylate) nanoparticles prepared throughmicrowave emulsion polymerization. J Appl Polym Sci 93:2815–2820

218. An Z, Tang W, Hawker CJ, Stucky GD (2006) One-step microwave preparation of well-defined and functionalized polymeric nanoparticles. J Am Chem Soc 128:15054–15055

219. Chiu T-P, Don T-M (2008) Synthesis and characterization of poly(methyl methacrylate)nanoparticles by emulsifier-free emulsion polymerization with a redox-initiated system.J Appl Polym Sci 109:3622–3630

220. Fang FF, Kim JH, Choi HJ, Kim CA (2009) Synthesis and electrorheological response ofnano-sized laponite stabilized poly(methyl methacrylate) spheres. Colloid Polym Sci287:745–749

221. Cui X, Zhong S, Wang H (2007) Emulsifier-free core-shell polyacrylate latex nanoparticlescontaining fluorine and silicon in shell. Polymer 48:7241–7248

222. Lee JM, Lee SJ, Jung YJ, Kim JH (2008) Fabrication of nano-structured polythiophenenanoparticles in aqueous dispersion. Curr Appl Phys 8:659–663

223. Wang S, Wang X, Zhang Z (2007) Preparation of polystyrene particles with narrow particlesize distribution by gamma-ray initiated miniemulsion polymerization stabilized bypolymeric surfactant. Eur Polym J 43:178–184

224. Bardajee GR, Vancaeyzeele C, Haley JC, Li AY, Winnik MA (2007) Synthesis,characterization, and energy transfer studies of dye-labeled poly(butyl methacrylate) latexparticles prepared by miniemulsion polymerization. Polymer 48:5839–5849

225. Rotureau E, Raynaud J, Choquenet B, Marie E, Nouvel C, Six J-L, Dellacherie E, Durand A(2008) Application of amphiphilic polysaccharides as stabilizers in direct and inverse free-radical miniemulsion polymerization. Colloids Surf A 331:84–90

226. Yildiz U, Landfester K (2008) Miniemulsion polymerization of styrene in the presence ofmacromonomeric initiators. Polymer 49:4930–4934

227. Ethirajan A, Ziener U, Landfester K (2009) Surface-functionalized polymeric nanoparticlesas templates for biomimetic mineralization of hydroxyapatite. Chem Mater 21:2218–2225

228. Crespy D, Landfester K (2009) Synthesis of polyvinylpyrrolidone/silver nanoparticleshybrid latex in non-aqueous miniemulsion at high temperature. Polymer 50:1616–1620

229. Wu M, Dellacherie E, Durand A, Marie E (2009) Poly(n-butyl cyanoacrylate) nanoparticlesvia miniemulsion polymerization (1): Dextran-based surfactants. Colloids Surf B 69:141–146

230. Baruch-Sharon S, Margel S (2010) Synthesis and characterization of polychloromethylstyrenenanoparticles of narrow size distribution by emulsion and miniemulsion polymerizationprocesses. Colloid Polym Sci 288:869–877

231. Jiang X, Dausend J, Hafner M, Musyanovych A, Röcker C, Landfester K, Mailänder V,Ulrich Nienhaus G (2010) Specific effects of surface amines on polystyrene nanoparticles intheir interactions with mesenchymal stem cells. Biomacromolecules 11:748–753

232. Antonietti M, Landfester K (2002) Polyreactions in miniemulsions. Prog Polym Sci 27:689–757

233. Landfester K, Willert M, Antonietti M (2000) Preparation of polymer particles innonaqueous direct and inverse miniemulsions. Macromolecules 33:2370–2376


234. Wormuth K (2001) Superparamagnetic latex via inverse emulsion polymerization. J ColloidInterface Sci 241:366–377

235. Oh JK, Tang C, Gao H, Tsarevsky NV, Matyjaszewski K (2006) Inverse miniemulsionATRP: a new method for synthesis and functionalization of well-defined water-soluble/cross-linked polymeric particles. J Am Chem Soc 128:5578–5584

236. Landfester K, Tiarks F, Hentze H-P, Antonietti M (2000) Polyaddition in miniemulsions: anew route to polymer dispersions. Macromol Chem Phys 201:1–5

237. Li C-YU, Chiu W-Y, Don T-M (2005) Preparation of polyurethane dispersions byminiemulsion polymerization. J Polym Sci Part A Polym Chem 43:4870–4881

238. Maitre C, Ganachaud F, Ferreira O, Lutz JF, Paintoux Y, Hémery P (2000) Anionicpolymerization of phenyl glycidyl ether in miniemulsion. Macromolecules 33:7730–7736

239. Tomov A, Broyer J-P, Spitz R (2000) Emulsion polymerization of ethylene in watermedium catalysed by organotransition metal complexes. Macromol Symp 150:53–58

240. Puig JE (1996) Microemulsion polymerization, In: Salamone JC (ed) Polymeric materialsencyclopedia, vol 6. CRC Press, New York, pp 4333–4341

241. Sosa N, Peralta RD, López RG, Ramos LF, Katime I, Cesteros C, Mendizábal E, Puig JE(2001) A comparison of the characteristics of poly(vinyl acetate) latex with high solidcontent made by emulsion and semi-continuous microemulsion polymerization. Polymer42:6923–6928

242. Sosa N, Zaragoza EA, López RG, Peralta RD, Katime I, Becerra F, Mendizábal E, Puig JE(2000) Unusual free radical polymerization of vinyl acetate in anionic microemulsionmedia. Langmuir 16:3612–3619

243. Kim B-J, Oh S-G, Han M-G, Im S–S (2000) Preparation of polyaniline nanoparticles inmicellar solutions as polymerization medium. Langmuir 16:5841–5845

244. Choi JW, Han MG, Kim SY, Oh SG, Im SS (2004) Poly(3,4-ethylenedioxythiophene)nanoparticles prepared in aqueous DBSA solutions. Synth Met 141:293–299

245. Han MG, Cho SK, Oh SG, Im SS (2002) Preparation and characterization of polyanilinenanoparticles synthesized from DBSA micellar solution. Synth Met 126:53–60

246. Li X-G, Huang M-R, Zeng J-F, Zhu M-F (2004) The preparation of polyaniline waterbornelatex nanoparticles and their films with anti-corrosivity and semi-conductivity. Colloids SurfA 248:111–120

247. Jang J, Oh JH, Stucky GD (2002) Fabrication of ultrafine conducting polymer and graphitenanoparticles. Angew Chem Int Ed 41:4016–4019

248. Lambert G, Bertrand JR, Fattal E, Subra F, Pinto-Alphandary H, Malvy C, Auclair C,Couvreur P (2000) EWS Fli-1 antisense nanocapsules inhibits Ewing sarcoma-related tumorin mice. Biochem Biophys Res Commun 279:401–406

249. Lambert G, Fattal E, Pinto-Alphandary H, Gulik A, Couvreur P (2000)Polyisobutylcyanoacrylate nanocapsules containing an aqueous core as a novel colloidalcarrier for the delivery of oligonucleotides. Pharm Res 17:707–714

250. Lambert G, Fattal E, Pinto-Alphandary H, Gulik A, Couvreur P (2001)Polyisobutylcyanoacrylate nanocapsules containing an aqueous core for the delivery ofoligonucleotides. Int J Pharm 214:13–16

251. Lambert G, Fattal E, Couvreur P (2001) Nanoparticulate systems for the delivery ofantisense oligonucleotides. Adv Drug Delivery Rev 47:99–112

252. Toub N, Angiari C, Eboué D, Fattal E, Tenu J-P, Le Doan T, Couvreur P (2005) Cellularfate of oligonucleotides when delivered by nanocapsules of poly(isobutylcyanoacrylate).J Controlled Release 106:209–213

253. Toub N, Bertrand J-R, Tamaddon A, Elhamess H, Hillaireau H, Maksimenko A, Maccario J,Malvy C, Fattal E, Couvreur P (2006) Efficacy of siRNA nanocapsules targeted against theEWS-Fli1 oncogene in Ewing sarcoma. Pharm Res 23:892–900

254. Hillaireau H, Le Doan T, Besnard M, Chacun H, Janin J, Couvreur P (2006) Encapsulationof antiviral nucleotide analogues azidothymidine-triphosphate and cidofovir in poly(iso-butylcyanoacrylate) nanocapsules. Int J Pharm 324:37–42

68 J. Allouche

255. Hillaireau H, Le Doan T, Chacun H, Janin J, Couvreur P (2007) Encapsulation of mono- andoligo-nucleotides into aqueous-core nanocapsules in presence of various water-solublepolymers. Int J Pharm 331:148–152

256. Anton N, Saulnier P, Gaillard C, Porcher E, Vrignaud S, Benoit J-P (2009) Aqueous-corelipid nanocapsules for encapsulating fragile hydrophilic and/or lipophilic molecules.Langmuir 25:11413–11419

257. Jang J, Bae J, Park E (2006) Selective fabrication of poly(3,4-ethylenedioxythiophene)nanocapsules and mesocellular foams using surfactant-mediated interfacial polymerization.Adv Mater 18:354–358

258. Landfester K (2001) The generation of nanoparticles in miniemulsions. Adv Mater 13:765–768

259. Tiarks F, Landfester K, Antonietti M (2001) Preparation of polymeric nanocapsules byminiemulsion polymerization. Langmuir 17:908–918

260. Al Khouri Fallouh N, Roblot-Treupel L, Fessi H (1986) Development of a new process forthe manufacture of polyisobutylcyanoacrylate nanocapsules. Int J Pharm 28:125–132

261. Al Khouri N, Fessi H, Roblot-Treupel L (1986) Original procedure for preparation ofnanocapsules of polyalkyl cyanoacrylates by interfacial polymerization. Pharm Acta Helv61:274–281

262. Rollot JM, Couvreur P, Roblo-Treupel L, Puisieux F (1986) Physicochemical andmorphological characterization of polyisobutyl cyanoacrylate nanocapsules. J Pharm Sci75:361–364

263. Chouinard F, Kan FWK, Leroux J-C, Foucher C, Lenaerts V (1991) Preparation andpurification of polyisohexylcyanoacrylate nanocapsules. Int J Pharm 72:211–217

264. Bouchemal K, Couenne F, Briançon S, Fessi H, Tayakout M (2006) Polyamidesnanocapsules: modelling and wall thickness estimation. AiChe 52:1–10

265. Takasu M, Kawaguchi H (2005) Preparation of colored latex with polyurea shell byminiemulsion polymerization. Colloid Polym Sci 283:805–811

266. Sirkar KK, Shanbhag PV, Kovvali AS (1999) Membrane in a reactor: a functionalperspective. Ind Eng Chem Res 38:3715–3737

267. Drioli E, Criscuoli A, Curcio E (2003) Membrane contactors and catalytic membranereactors in process intensification. Chem Eng Technol 26:975–981

268. Charcosset C, Fessi H (2006) A membrane contactor for the preparation of nanoparticles.Desalination 200:568–569

269. Yanagishita T, Fujimura R, Nishio K, Masuda H (2010) Fabrication of monodispersepolymer nanoparticles by membrane emulsification using ordered anodic porous alumina.Langmuir 26:1516–1519

270. Matyjaszewski K, Xia J (2001) Atom transfer radical polymerization. Chem Rev 101:2921–2990

271. Zetterlund PB, Kagawa Y, Okubo M (2008) Controlled/living radical polymerization indispersed systems. Chem Rev 108:3747–3794

272. Zetterlund PB, Nakamura T, Okubo M (2007) Mechanistic investigation of particle sizeeffects in TEMPO-mediated radical polymerization of styrene in aqueous miniemulsion.Macromolecules 40:8663–8672

273. Nicolas J, Ruzette A-V, Farcet C, Gérard P, Magnet S, Charleux B (2007) Nanostructuredlatex particles synthesized by nitroxide-mediated controlled/living free-radicalpolymerization in emulsion. Polymer 48:7029–7040

274. Dire C, Magnet S, Couvreur L, Charleux B (2009) Nitroxide-mediated controlled/livingfree-radical surfactant-free emulsion polymerization of methyl methacrylate using apoly(methacrylie acid)-based macroalkoxyamine initiator. Macromolecules 42:95–103

275. Farcet C, Nicolas J, Charleux B (2002) Kinetic study of the nitroxide-mediated controlledfree-radical polymerization of n-butyl acrylate in aqueous miniemulsions. J Polym Sci PartA Polym Chem 40:4410–4420

276. Farcet C, Charleux B, Pirri R (2001) Poly(n-butyl acrylate) homopolymer and poly[n-butylacrylate-b-(n-butyl acrylate-co-styrene)] block copolymer prepared via nitroxide-mediated


living/controlled radical polymerization in miniemulsion [6]. Macromolecules 34:3823–3826

277. Farcet C, Lansalot M, Charleux B, Pirri R, Vairon JP (2000) Mechanistic aspects ofnitroxide-mediated controlled radical polymerization of styrene in miniemulsion, using awater-soluble radical initiator. Macromolecules 33:8559–8570

278. Li W, Matyjaszewski K, Albrecht K, Möller M (2009) Reactive surfactants for polymericnanocapsules via interfacially confined miniemulsion ATRP. Macromolecules 42:8228–8233

279. Siegwart DJ, Srinivasan A, Bencherif SA, Karunanidhi A, Jung KO, Vaidya S, Jin R,Hollinger JO, Matyjaszewski K (2009) Cellular uptake of functional nanogels prepared byinverse miniemulsion ATRP with encapsulated proteins, carbohydrates, and goldnanoparticles. Biomacromolecules 10:2300–2309

280. Oh JK, Perineau F, Charleux B, Matyjaszewski K (2009) AGET ATRP in water and inverseminlemulsion: A facile route for preparation of high-molecular-weight biocompatiblebrush-like polymers. J Polym Sci Part A Polym Chem 47:1771–1781

281. Li W, Min K, Matyjaszewski K, Stoffelbach F, Charleux B (2008) PEO-based blockcopolymers and homopolymers as reactive surfactants for AGET ATRP of butyl acrylate inminiemulsion. Macromolecules 41:6387–6392

282. Min K, Gao H, Yoon JA, Wu W, Kowalewski T, Matyjaszewski K (2009) One-pot synthesisof hairy nanoparticles by emulsion ATRP. Macromolecules 42:1597–1603

283. Min K, Gao H, Matyjaszewski K (2006) Development of an ab initio emulsion atom transferradical polymerization: from microemulsion to emulsion. J Am Chem Soc 128:10521–10526

284. Min K, Matyjaszewski K (2005) Atom transfer radical polymerization in microemulsion.Macromolecules 38:8131–8134

285. Rieger J, Zhang W, Stoffelbach F, Charleux B (2010) Surfactant-free RAFT emulsionpolymerization using poly(N,N -dimethylacrylamide) trithiocarbonate macromolecularchain transfer agents. Macromolecules 43:6302–6310

286. Manguian M, Save M, Charleux B (2006) Batch emulsion polymerization of styrenestabilized by a hydrophilic macro-RAFT agenta. Macromol Rapid Commun 27:399–404

287. Zhou X, Ni P, Yu Z (2007) Comparison of RAFT polymerization of methyl methacrylate inconventional emulsion and miniemulsion systems. Polymer 48:6262–6271

288. Nicolas J, Charleux B, Guerret O, Magnet S (2005) Nitroxide-mediated controlled free-radical emulsion polymerization using a difunctional water-soluble alkoxyamine initiator.Toward the control of particle size, particle size distribution, and the synthesis of triblockcopolymers. Macromolecules 38:9963–9973

289. Dalpiaz A, Vighi E, Pavan B, Leo E (2009) Fabrication via a nonaqueous nanoprecipitationmethod, characterization and in vitro biological behavior of N6-cyclopentyladenosine-loaded nanoparticles. J Pharm Sci 98:4272–4284

290. Cheng F-Y, Wang SP-H, Su C-H, Tsai T-L, Wu P-C, Shieh D-B, Chen J-H, Hsieh PC-H,Yeh C-S (2008) Stabilizer-free poly(lactide-co-glycolide) nanoparticles for multimodalbiomedical probes. Biomaterials 29:2104–2112

291. Murakami H, Kobayashi M, Takeuchi H, Kawashima Y (1999) Preparation of poly(DL-lactide-co-glycolide) nanoparticles by modified spontaneous emulsification solventdiffusion method. Int J Pharm 187:143–152

292. Chang J, Jallouli Y, Kroubi M, Yuan X-b, Feng W, Kang C-s, Pu P-y, Betbeder D (2009)Characterization of endocytosis of transferrin-coated PLGA nanoparticles by the blood-brain barrier. Int J Pharm 379: 285–292

293. Nassar T, Rom A, Nyska A, Benita S (2009) Novel double coated nanocapsules forintestinal delivery and enhanced oral bioavailability of tacrolimus, a P-gp substrate drug.J Controlled Release 133:77–84

294. de Assis DN, Mosqueira VCF, Vilela JMC, Andrade MS, Cardoso VN (2008) Releaseprofiles and morphological characterization by atomic force microscopy and photoncorrelation spectroscopy of 99mTechnetium-fluconazole nanocapsules. Int J Pharm349:152–160

70 J. Allouche

295. Limayem Blouza I, Charcosset C, Sfar S, Fessi H (2006) Preparation and characterization ofspironolactone-loaded nanocapsules for paediatric use. Int J Pharm 325:124–131

296. Moinard-Chécot D, Chevalier Y, Briançon S, Beney L, Fessi H (2008) Mechanism ofnanocapsules formation by the emulsion-diffusion process. J Colloid Interface Sci 317:458–468

297. Zili Z, Sfar S, Fessi H (2005) Preparation and characterization of poly-epsilon-caprolactonenanoparticles containing griseofulvin. Int J Pharm 294:261–267

298. Kim E, Yang J, Choi J, Suh J-S, Huh Y-M, Haam S (2009) Synthesis of gold nanorod-embedded polymeric nanoparticles by a nanoprecipitation method for use as photothermalagents. Nanotechnology. 20: 365602 (p 7)

299. Ferranti V, Marchais H, Chabenat C, Orecchioni AM, Lafont O (1999) Primidone-loadedpoly-epsilon-caprolactone nanocapsules: incorporation efficiency and in vitro releaseprofiles. Int J Pharm 193:107–111

300. Seyler I, Appel M, Devissaguet J-P, Legrand P, Barratt G (1999) Macrophage activation bya lipophilic derivative of muramyldipeptide within nanocapsules: Investigation of themechanism of drug delivery. J Nanopart Res 1:91–97

301. Legrand P, Lesieur S, Bochot A, Gref R, Raatjes W, Barratt G, Vauthier C (2007) Influenceof polymer behaviour in organic solution on the production of polylactide nanoparticles bynanoprecipitation. Int J Pharm 344:33–43

302. Nehilla BJ, Bergkvist M, Popat KC, Desai TA (2008) Purified and surfactant-free coenzymeQ10-loaded biodegradable nanoparticles. Int J Pharm 348:107–114

303. Yallapu MM, Gupta BK, Jaggi M, Chauhan SC (2010) Fabrication of curcuminencapsulated PLGA nanoparticles for improved therapeutic effects in metastatic cancercells. J Colloid Interface Sci 351:19–29

304. Deepak V, Ram Kumar Pandian SB, Kalishwaralal K, Gurunathan S (2009) Purification,immobilization, and characterization of nattokinase on PHB nanoparticles. BioresourTechnol 100: 6644–6646

305. Duclairoir C, Nakache E, Marchais H, Orecchioni A-M (1998) Formation of gliadinnanoparticles: Influence of the solubility parameter of the protein solvent. Colloid PolymSci 276:321–327

306. Skiba M, Wouessidjewe D, Puisieux F, Duchêne D, Gulik A (1996) Characterization ofamphiphilic beta-cyclodextrin nanospheres. Int J Pharm 142:121–124

307. Lannibois H, Hasmy A, Botet R, Chariol OA, Cabane B (1997) Surfactant limitedaggregation of hydrophobic molecules in water. J Phys I 7:319–342

308. Jeong Y-I, Cho C-S, Kim S-H, Ko K-S, Kim S-I, Shim Y-H, Nah J-W (2001) Preparation ofpoly(DL-lactide-co-glycolide) nanoparticles without surfactant. J Appl Polym Sci 80:2228–2236

309. Kostag M, Köhler S, Liebert T, Heinze T (2010) Pure cellulose nanoparticles fromtrimethylsilyl cellulose. Macromol Symp 294:96–106

310. Jeon H-J, Jeong Y-I, Jang M-K, Park Y-H, Nah J-W (2000) Effect of solvent on thepreparation of surfactant-free poly(DL-lactide-co-glycolide) nanoparticles and norfloxacinrelease characteristics. Int J Pharm 207:99–108

311. Akagi T, Kaneko T, Kida T, Akashi M (2005) Preparation and characterization ofbiodegradable nanoparticles based on poly(gamma-glutamic acid) with L-phenylalanine as aprotein carrier. J Controlled Release 108:226–236

312. Lee J, Cho EC, Cho K (2004) Incorporation and release behavior of hydrophobic drug infunctionalized poly(D,L-lactide)-block-poly(ethylene oxide) micelles. J Controlled Release94:323–335

313. Chronopoulou L, Fratoddi I, Palocci C, Venditti I, Russo MV (2009) Osmosis based methoddrives the self-assembly of polymeric chains into micro-and nanostructures. Langmuir25:11940–11946

314. Na K, Lee KH, Lee DH, Bae YH (2006) Biodegradable thermo-sensitive nanoparticles frompoly(L-lactic acid)/poly(ethylene glycol) alternating multi-block copolymer for potentialanti-cancer drug carrier. Eur J Pham Sci 27:115–122


315. Hornig S, Heinze T (2008) Efficient approach to design stable water-dispersiblenanoparticles of hydrophobic cellulose esters. Biomacromolecules 9:1487–1492

316. Marty JJ, Oppenheim RC, Speiser P (1978) Nanoparticles–a new colloidal drug deliverysystem. Pharm Acta Helv 53:17–23

317. Kommareddy S, Amiji MM (2007) Protein nanospheres for gene delivery: preparation andin vitro transfection studies with gelatin nanoparticles. Gene transfer. Cold Spring HarborLaboratory Press, New York, pp 527–540

318. Weber C, Coester C, Kreuter J, Langer K (2000) Desolvation process and surfacecharacterisation of protein nanoparticles. Int J Pharm 194:91–102

319. Weber C, Kreuter J, Langer K (2000) Desolvation process and surface characteristics ofHSA-nanoparticles. Int J Pharm 196:197–200

320. Langer K, Anhorn MG, Steinhauser I, Dreis S, Celebi D, Schrickel N, Faust S, Vogel V(2008) Human serum albumin (HSA) nanoparticles: reproducibility of preparation processand kinetics of enzymatic degradation. Int J Pharm 347:109–117

321. Langer K, Balthasar S, Vogel V, Dinauer N, von B, Schubert D (2003) Optimization of thepreparation process for human serum albumin (HSA) nanoparticles. Int J Pharm 257:169–180

322. Wartlick H, Spankuch-Schmitt B, Strebhardt K, Kreuter J, Langer K (2004) Tumour celldelivery of antisense oligonucleotides by human serum albumin nanoparticles. J ControlledRelease 96:483–495

323. Mo Y, Barnett ME, Takemoto D, Davidson H, Kompella UB (2007) Human serum albuminnanoparticles for efficient delivery of Cu, Zn superoxide dismutase gene. Mol Vis 13:746–757

324. Li F-Q, Su H, Wang J, Liu J-Y, Zhu Q-G, Fei Y-B, Pan Y-H, Hu J-H (2008) Preparation andcharacterization of sodium ferulate entrapped bovine serum albumin nanoparticles for livertargeting. Int J Pharm 349:274–282

325. Zhao D, Zhao X, Zu Y, Li J, Zhang Y, Jiang R, Zhang Z (2010) Preparation,characterization, and in vitro targeted delivery of folate-decorated paclitaxel-loadedbovine serum albumin nanoparticles. Int J Nanomed 5:669–677

326. Duclairoir C, Irache JM, Nakache E, Orecchioni A-M, Chabenat C, Popineau Y (1999)Gliadin nanoparticles: formation, all-trans-retinoic acid entrapment and release, sizeoptimization. Polym Int 48:327–333

327. Umamaheshwari RB, Jain NK (2003) Receptor mediated targeting of lectin conjugatedgliadin nanoparticles in the treatment of Helicobacter pylori. J Drug Target 11:415–424

328. Ramteke S, Jain NK (2008) Clarithromycin- and omeprazole-containing gliadinnanoparticles for the treatment of Helicobacter pylori. J Drug Target 16:65–72

329. Coester CJ, Langer K, van Briesen H, Kreuter J (2000) Gelatin nanoparticles by twostep desolvation a new preparation method, surface modifications and cell uptake.J Microencapsul 17:187–193

330. Coester C, Kreuter J, von B, Langer K (2000) Preparation of avidin-labeled gelatinnanoparticles as carriers for biotinylated peptide nucleic acid (PNA). Int J Pharm 196:147–149

331. Vandervoort J, Ludwig A (2004) Preparation and evaluation of drug-loaded gelatinnanoparticles for topical ophthalmic use. Eur J Pharm Biopharm 57:251–261

332. Balthasar S, Michaelis K, Dinauer N, von B, Kreuter J, Langer K (2005) Preparation andcharacterization of antibody modified gelatin nanoparticles as drug carrier system for uptakein lymphocytes. Biomaterials 26:2723–2732

333. Azarmi S, Huang Y, Chen H, McQuarrie S, Abrams D, Roa W, Finlay WH, Miller GG,Lobenberg R (2006) Optimization of a two-step desolvation method for preparing gelatinnanoparticles and cell uptake studies in 143B osteosarcoma cancer cells. J Pharm Pharm Sci9:124–132

334. Saraogi GK, Gupta P, Gupta UD, Jain NK, Agrawal GP (2010) Gelatin nanocarriers aspotential vectors for effective management of tuberculosis. Int J Pharm 385:143–149

335. Taheri Qazvini N, Zinatloo S (2011) Synthesis and characterization of gelatin nanoparticlesusing CDI/NHS as a non-toxic cross-linking system. J Mater Sci Mater Med 22:63–69

72 J. Allouche

336. Zwiorek K, Kloeckner J, Wagner E, Coester C (2004) Gelatin nanoparticles as a new andsimple gene delivery system. J Pharm Pharm Sci 7:22–28

337. Agnihotri SA, Aminabhavi TM (2007) Chitosan nanoparticles for prolonged delivery oftimolol maleate. Drug Dev Ind Pharm 33:1254–1262

338. Al-Ghananeem AM, Malkawi AH, Muammer YM, Balko JM, Black EP, Mourad W,Romond E (2009) Intratumoral delivery of paclitaxel in solid tumor from biodegradablehyaluronan nanoparticle formulations. AAPS PharmSciTech 10:410–417

339. De Martimprey H, Vauthier C, Malvy C, Couvreur P (2009) Polymer nanocarriers for thedelivery of small fragments of nucleic acids: oligonucleotides and siRNA. Eur J PharmBiopharm 71:490–504

340. Howard KA, Kjems J (2007) Polycation-based nanoparticle delivery for improved RNAinterference therapeutics. Expert Opin Biol Ther 7:1811–1822

341. Rajaonarivony M, Vauthier C, Couarraze G, Puisieux F, Couvreur P (1993) Development ofa new drug carrier made from alginate. J Pharm Sci 82:912–917

342. Schatz C, Domard A, Viton C, Pichot C, Delair T (2004) Versatile and efficient formation ofcolloids of biopolymer-based polyelectrolyte complexes. Biomacromolecules 5:1882–1892

343. Drogoz A, David L, Rochas C, Domard A, Delair T (2007) Polyelectrolyte complexes frompolysaccharides: formation and stoichiometry monitoring. Langmuir 23:10950–10958

344. Drogoz A, Munier S, Verrier B, David L, Domard A, Delair T (2008) Towardsbiocompatible vaccine delivery systems: Interactions of colloidal PECs based onpolysaccharides with HIV-1 p24 antigen. Biomacromolecules 9:583–591

345. Daoud-Mahammed S, Ringard-Lefebvre C, Razzouq N, Rosilio V, Gillet B, Couvreur P,Amiel C, Gref R (2007) Spontaneous association of hydrophobized dextran and poly-beta-cyclodextrin into nanoassemblies. Formation and interaction with a hydrophobic drug.J Colloid Interface Sci 307:83–93

346. Gref R, Amiel C, Molinard K, Daoud-Mahammed S, Sébille B, Gillet B, Beloeil J-C, RingardC, Rosilio V, Poupaert J, Couvreur P (2006) New self-assembled nanogels based on host-guestinteractions: characterization and drug loading. J Controlled Release 111:316–324

347. Boissière M, Meadows PJ, Brayner R, Hélary C, Livage J, Coradin T (2006) Turningbiopolymer particles into hybrid capsules: the example of silica/alginate nanocomposites.J Mater Chem 16:1178–1182

348. De S, Robinson D (2003) Polymer relationships during preparation of chitosan-alginate andpoly-L-lysine-alginate nanospheres. J Controlled Release 89:101–112

349. Aynie I, Vauthier C, Chacun H, Fattal E, Couvreur P (1999) Spongelike alginatenanoparticles as a new potential system for the delivery of antisense oligonucleotides.Antisense Nucleic Acid Drug Dev 9:301–312

350. González Ferreiro M, Tillman L, Hardee G, Bodmeier R (2002) Characterization ofalginate/poly-L-lysine particles as antisense oligonucleotide carriers. Int J Pharm 239:47–59

351. Douglas KL, Tabrizian M (2005) Effect of experimental parameters on the formation ofalginate-chitosan nanoparticles and evaluation of their potential application as DNA carrier.J Biomater Sci Polym Ed 16:43–56

352. Sarmento B, Ribeiro AJ, Veiga F, Ferreira DC, Neufeld RJ (2007) Insulin-loadednanoparticles are prepared by alginate lonotropic pre-gelation followed by chitosanpolyelectrolyte complexation. J Nanosci Nanotechnol 7:2833–2841

353. Das RK, Kasoju N, Bora U (2010) Encapsulation of curcumin in alginate-chitosan-pluroniccomposite nanoparticles for delivery to cancer cells. Nanomedicine 6:153–160

354. Li P, Dai Y-N, Zhang J-P, Wang A-Q, Wei Q (2008) Chitosan-alginate nanoparticles as anovel drug delivery system for nifedipine. Int J Biomed Sci 4:221–228

355. Sarmento B, Ferreira DC, Jorgensen L, van de Weert M (2007) Probing insulin’s secondarystructure after entrapment into alginate/chitosan nanoparticles. Eur J Pharm Biopharm 65:10–17

356. Sarmento B, Ribeiro A, Veiga F, Sampaio P, Neufeld R, Ferreira D (2007) Alginate/chitosan nanoparticles are effective for oral insulin delivery. Pharm Res 24:2198–2206


357. Sarmento B, Ferreira D, Veiga F, Ribeiro A (2006) Characterization of insulin-loadedalginate nanoparticles produced by ionotropic pre-gelation through DSC and FTIR studies.Carbohydr Polym 66:1–7

358. Calvo P, Remuñan-López C, Vila-Jato JL, Alonso MJ (1997) Chitosan and chitosan/ethylene oxide-propylene oxide block copolymer nanoparticles as novel carriers for proteinsand vaccines. Pharm Res 14:1431–1436

359. Calvo P, Remuñán-López C, Vila-Jato JL, Alonso MJ (1997) Novel hydrophilic chitosan-polyethylene oxide nanoparticles as protein carriers. J Appl Polym Sci 63:125–132

360. López-León T, Carvalho ELS, Seijo B, Ortega-Vinuesa JL, Bastos-González D (2005)Physicochemical characterization of chitosan nanoparticles: electrokinetic and stabilitybehavior. J Colloid Interface Sci 283:344–351

361. Fernández-Urrusuno R, Calvo P, Remuñán-López C, Vila-Jato JL, Alonso MJ (1999)Enhancement of nasal absorption of insulin using chitosan nanoparticles. Pharm Res16:1576–1581

362. Cetin M, Aktas Y, Vural I, Capan Y, Dogan LA, Duman M, Dalkara T (2007) Preparationand in vitro evaluation of bFGF-loaded chitosan nanoparticles. Drug Deliv 14:525–529

363. Janes KA, Calvo P, Alonso MJ (2001) Polysaccharide colloidal particles as delivery systemsfor macromolecules. Adv Drug Delivery Rev 47:83–97

364. Katas H, Alpar HO (2006) Development and characterisation of chitosan nanoparticles forsiRNA delivery. J Controlled Release 115:216–225

365. Dung TH, Lee S-R, Han S-D, Kim S-J, Ju Y-M, Kim M-S, Yoo H (2007) Chitosan-TPPnanoparticle as a release system of antisense oligonucleotide in the oral environment.J Nanosci Nanotechnol 7:3695–3699

366. Reverchon E (1999) Supercritical antisolvent precipitation of micro- and nano-particles.J Supercrit Fluids 15:1–21

367. Jung J, Perrut M (2001) Particle design using supercritical fluids: literature and patentsurvey. J Supercrit Fluids 20:179–219

368. Vemavarapu C, Mollan MJ, Lodaya M, Needham TE (2005) Design and process aspects oflaboratory scale SCF particle formation systems. Int J Pharm 292:1–16

369. Mishima K (2008) Biodegradable particle formation for drug and gene delivery usingsupercritical fluid and dense gas. Adv Drug Deliv Rev 60:411–432

370. Kawashima Y (2001) Panoparticulate systems for improved drug delivery. Adv Drug DelivRev 47:1–2

371. Weber M, Thies MC (2002) Understanding the RESS process. In: Sun Y-P (ed)Supercritical fluid technology in materials science and engineering: synthesis, properties,and applications. CRC press, New York, pp 387–437

372. Blasig A, Shi C, Enick RM, Thies MC (2002) Effect of concentration and degree ofsaturation on RESS of a CO2-soluble fluoropolymer. Ind Eng Chem Res 41:4976–4983

373. Sane A, Thies MC (2007) Effect of material properties and processing conditions on RESSof poly(l-lactide). J Supercrit Fluids 40:134–143

374. Sun Y-P, Rollins HW, Jayasundera B, Meziani MJ, Bunker CE (2002) Preparation andprocessing of nanoscale materials by supercritical fluid technology. In: Sun Y-P (ed)Supercritical fluid technology in materials science and engineering: synthesis, properties,and applications. CRC Press, New York, pp 491–576

375. Meziani MJ, Pathak P, Hurezeanu R, Thies MC, Enick RM, Sun Y-P (2004) Supercritical-fluidprocessing technique for nanoscale polymer particles. Angew Chem Int Ed 43:704–707

376. Meziani MJ, Pathak P, Wang W, Desai T, Patil A, Sun Y-P (2005) Polymeric nanofibersfrom rapid expansion of supercritical solution. Ind Eng Chem Res 44:4594–4598

377. Vehring R (2008) Pharmaceutical particle engineering via spray drying. Pharm Res 25:999–1022

378. Schuck P, Dolivet A, Méjean S, Zhu P, Blanchard E, Jeantet R (2009) Drying by desorption:a tool to determine spray drying parameters. J Food Eng 94:199–204

379. Arpagaus C, Schafroth N (2009) Laboratory scale spray drying of biodegradable polymers.Respir Drug Deliv Eur 2:269–274

74 J. Allouche

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